Resistor and method of manufacturing the same

ABSTRACT

The present invention relates to a resistor and a manufacturing method of the same. The invention aims at providing the resistor and the manufacturing method thereof that can reduce a soldering area that occupies a mount area, when the resistor is mounted on a mount board. In order to achieve the foregoing object, a resistor comprises a substrate ( 21 ), a pair of first upper surface electrode layers ( 22 ), each provided on a side portion of an upper surface toward a portion of a side surface of the substrate ( 21 ), a pair of second upper surface electrode layers ( 23 ) provided in a manner to make electrical connections with the first upper surface electrode layers ( 22 ), a resistance layer ( 24 ) provided in a manner to make electrical connections with the second surface electrode layers ( 23 ), and a protective layer ( 25 ) provided to cover at least an upper surface of the resistance layer ( 24 ). The invention realizes the electrodes on side surfaces of the resistor to have a small surface area because of the pair of first surface electrode layers ( 22 ) on side portions of an upper surface toward portions of side surfaces of the substrate ( 21 ), thereby attaining a reduction of the actual mount area on the mount board, including soldering portions.

This application is a U.S. national phase application of PCTINTERNATIONAL application PCT/JP98/02989.

FIELD OF THE INVENTION

The present invention relates to a resistor and a method ofmanufacturing the same.

BACKGROUND OF THE INVENTION

There has been a growing demand more than ever in recent years forminiaturization of electronic components used for circuit boards, inorder to increase a density of mounting, as reduction in size ofelectronic devices continues. A demand has been rising also forresistors having smaller size and higher accuracy in tolerance ofresistance values, in order to reduce mounting areas on mount boards.

Previously known resistors of such kind include one that is disclosed inJapanese Patent Laid-open Publication, Number H04-102302.

A resistor of the prior art and a method of manufacturing the same willbe described hereinafter by referring to accompanying figures.

FIG. 50 is a sectional view depicting a resistor of the prior art.

In the figure, a reference numeral 1 represents an insulating substrate,and a reference numeral 2 represents first upper surface electrodelayers provided on an upper surface at both right and left ends of theinsulating substrate 1. A reference numeral 3 represents a resistancelayer provided in a manner that portions of which overlap with the firstupper surface electrode layers 2. A reference numeral 4 represents afirst protective layer provided in a manner to cover the resistancelayer 3 entirely. A reference numeral 5 represents a trimmed slitprovided in the resistance layer 3 and the first protective layer 4 forcorrecting a resistance value. A reference numeral 6 represents a secondprotective layer provided over an outer surface of the first protectivelayer 4. A reference numeral 7 represents second upper surface electrodelayers provided on upper surfaces of the first upper surface electrodelayers 2 in a manner to spread over a full width of the insulatingsubstrate 1. A reference numeral 8 represents side surface electrodelayers provided on side surfaces of the insulating substrate 1.Reference numerals 9 and 10 respectively represent nickel-plated layersand solder-plated layers provided over surfaces of the second uppersurface electrode layers 7 and the side surface electrode layers 8.

A method of manufacturing the resistor of the prior art constructed asabove will be described hereinafter by referring to accompanyingfigures.

FIG. 51 represents procedural views depicting a method of manufacturingthe prior art resistor.

Firstly, first upper surface electrode layers 2 are print-formed on bothright and left ends of an upper surface of an insulating substrate 1, asshown in FIG. 51(a).

Secondly, a resistance layer 3 is print-formed on the upper surface ofthe insulating substrate 1 in a manner that portions of which overlapwith the first upper surface electrode layers 2, as shown in FIG. 51(b).

Then, a first protective layer 4 is print-formed to cover the resistancelayer 3 entirely, followed by providing a trimmed slit 5 in theresistance layer 3 and the first protective layer 4 with a laser or thelike, as shown in FIG. 51(c), in order to make a resistance value of theresistance layer 3 to fall within a predetermined range of resistancevalue.

A second protective layer 6 is then print-formed on an upper surface ofthe first protective layer 4 as shown in FIG. 51(d).

Second upper surface electrode layers 7 are then print-formed on uppersurfaces of the first upper surface electrode layers 2 in a manner thatthey spread over an entire width of the insulating substrate 1 as shownin FIG. 51(e).

Side surface electrode layers 8 are coat-formed on side surfaces at bothright and left ends of the first upper surface electrode layers 2 andthe insulating substrate 1, in a manner to make an electrical continuitywith the first and the second upper surface electrode layers 2 and 7, asshown in FIG. 51(f).

The resistor of the prior art is completed finally, when nickel-platedlayers 9 and solder-plated layers 10 are formed by providingsolder-plating after nickel-plating over surfaces of the second uppersurface electrode layers 7 and the side surface electrode layers 8.

However, as shown in a sectional view of FIG. 52(a) depicting theresistor of the prior art in a mounted position, the resistor having theabove structure of the prior art and produced by the manufacturingmethod described above has a fillet-mounting structure, in which it issoldered with both the side surface electrode layers (not shown in thefigure) and the lower surface electrode layers (not shown in thefigure), when it is soldered on a mount board. The resistor thusrequires areas 13 for soldering the side surfaces in addition to an area12 for the resistor component, and therefore a mounting area 14combining them altogether, as shown in a plan view of FIG. 52(b)depicting of the resistor of the prior art. Furthermore, a proportionoccupied by the soldering area with respect to the mounting areaincreases, if external dimensions of the component are reduced in orderto increase a density of mounting. Consequently, the resistor has aproblem that a limitation arises in the improvement of mounting densityin order to reduce size of electronic devices.

The present invention is intended to solve the above-described problemof the prior art, and it aims at providing a resistor, as well as amethod of manufacturing, that can reduce a soldering area occupying inthe mounting area, when it is mounted on the mount board.

DISCLOSURE OF THE INVENTION

In order to solve the foregoing problem, a resistor of the presentinvention comprises: a substrate; a pair of first upper surfaceelectrode layers provided on side portions of an upper surface toward aportion of respective side surfaces of the substrate; a pair of secondupper surface electrode layers provided in a manner to make electricalconnections with the first upper surface electrode layers; a resistancelayer provided in a manner to make electrical connections with thesecond upper surface electrode layers; and a protective layer providedto cover at least an upper surface of the resistance layer.

In the above-described resistor, electrodes on side surfaces of theresistor have small surface areas, since the resistor is provided withthe pair of first upper surface electrode layers on side portions of theupper surface toward portions of side surfaces of the substrate. Becausethe resistor is soldered with the small areas of the electrodes on sidesurfaces, it can reduce an area required to form fillets for soldering,if it is soldered on a mount board. Accordingly, the resistor is able toreduce a mount area, including soldering portions, on the mount board.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view depicting a resistor of a first exemplaryembodiment of the present invention;

FIG. 2(a) through FIG. 2(c) represent a series of procedural viewsdepicting a process of manufacturing the same resistor;

FIG. 3(a) through FIG. 3(d) represent another series of procedural viewsdepicting the process of manufacturing the same resistor;

FIG. 4(a) is a sectional view depicting the same resistor in a mountedposition;

FIG. 4(b) is a plan view depicting the same resistor in the mountedposition;

FIG. 5 is a sectional view depicting a resistor of a second exemplaryembodiment of the present invention;

FIG. 6(a) through FIG. 6(c) represent a series of procedural viewsdepicting a process of manufacturing the same resistor;

FIG. 7(a) through FIG. 7(d) represent another series of procedural viewsdepicting the process of manufacturing the same resistor;

FIG. 8 is a sectional view depicting a resistor of a third exemplaryembodiment of the present invention;

FIG. 9(a) through FIG. 9(c) represent a series of procedural viewsdepicting a process of manufacturing the same resistor;

FIG. 10(a) through FIG. 10(c) represent another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 11(a) and FIG. 11(b) represent still another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 12(a) is a sectional view depicting the same resistor in a mountedposition; and

FIG. 12(b) is a plan view depicting the same resistor in the mountedposition;

FIG. 13 is a sectional view depicting a resistor of a fourth exemplaryembodiment of the present invention;

FIG. 14(a) through FIG. 14(c) represent a series of procedural viewsdepicting a process of manufacturing the same resistor;

FIG. 15(a) through FIG. 15(c) represent another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 16(a) and FIG. 16(b) represent still another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 17 is a sectional view depicting a resistor of a fifth exemplaryembodiment of the present invention;

FIG. 18(a) through FIG. 18(c) represent a series of procedural viewsdepicting a process of manufacturing the same resistor;

FIG. 19(a) through FIG. 19(c) represent another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 20(a) and FIG. 20(b) represent still another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 21 is a sectional view depicting a resistor of a sixth exemplaryembodiment of the present invention;

FIG. 22(a) through FIG. 22(c) represent a series of procedural viewsdepicting a process of manufacturing the same resistor;

FIG. 23(a) and FIG. 23(b) represent another series of procedural viewsdepicting the process of manufacturing the same resistor;

FIG. 24(a) and FIG. 24(b) represent still another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 25(a) is a sectional view depicting the same resistor in a mountedposition;

FIG. 25(b) is a plan view depicting the same resistor in the mountedposition;

FIG. 26 is a sectional view depicting a resistor of a seventh exemplaryembodiment of the present invention;

FIG. 27(a) through FIG. 27(c) represent a series of procedural viewsdepicting a process of manufacturing the same resistor;

FIG. 28(a) through FIG. 28(c) represent another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 29(a) and FIG. 29(b) represent still another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 30 is a sectional view depicting a resistor of an eighth exemplaryembodiment of the present invention;

FIG. 31(a) through FIG. 31(c) represent a series of procedural viewsdepicting a process of manufacturing the same resistor;

FIG. 32(a) through FIG. 32(c) represent another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 33(a) is a sectional view depicting the same resistor in a mountedposition;

FIG. 33(b) is a plan view depicting the same resistor in the mountedposition;

FIG. 34 is a sectional view depicting a resistor of a ninth exemplaryembodiment of the present invention;

FIG. 35(a) through FIG. 35(c) represent a series of procedural viewsdepicting a process of manufacturing the same resistor;

FIG. 36(a) through FIG. 36(c) represent another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 37 is a sectional view depicting a resistor of a tenth exemplaryembodiment of the present invention;

FIG. 38(a) through FIG. 38(c) represent a series of procedural viewsdepicting a process of manufacturing the same resistor;

FIG. 39(a) through FIG. 39(c) represent another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 40(a) is a sectional view depicting the same resistor in a mountedposition;

FIG. 40(b) is a plan view depicting the same resistor in the mountedposition;

FIG. 41 is a sectional view depicting a resistor of an eleventhexemplary embodiment of the present invention;

FIG. 42(a) through FIG. 42(c) represent a series of procedural viewsdepicting a process of manufacturing the same resistor;

FIG. 43(a) through FIG. 43(d) represent another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 44 is a sectional view depicting a resistor of a twelfth exemplaryembodiment of the present invention;

FIG. 45(a) through FIG. 45(c) represent a series of procedural viewsdepicting a process of manufacturing the same resistor;

FIG. 46(a) through FIG. 46(d) represent another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 47 is a sectional view depicting a resistor of a thirteenthexemplary embodiment of the present invention;

FIG. 48(a) through FIG. 48(c) represent a series of procedural viewsdepicting a process of manufacturing the same resistor;

FIG. 49(a) through FIG. 49(d) represent another series of proceduralviews depicting the process of manufacturing the same resistor;

FIG. 50 is a sectional view depicting a resistor of the prior art;

FIG. 51(a) through FIG. 51(f) represent a series of procedural viewsdepicting a process of manufacturing the same resistor;

FIG. 52(a) is a sectional view depicting the same resistor in a mountedposition; and

FIG. 52(b) is a plan view depicting the same resistor in the mountedposition.

THE BEST MODE FOR CARRYING OUT THE INVENTION First Exemplary Embodiment

A resistor of a first exemplary embodiment of the present invention anda method of manufacturing the same will be described hereinafter byreferring to accompanying figures.

FIG. 1 is a sectional view of a resistor of the first exemplaryembodiment of this invention.

In the figure, a reference numeral 21 represents a substrate containing96% of alumina. A reference numeral 22 represents first upper surfaceelectrode layers, which are constructed of calcined gold-base organicmetal compound, and provided on side portions of an upper surface towardportions of side surfaces of the substrate 21. Ridges of these firstupper surface electrode layers 22 are rounded. In addition, a surfacearea of the first upper surface electrode layer 22 occupying the sidesurface of the substrate 21 is not more than a half of an area of theside surface of the substrate 21. A reference numeral 23 representssecond upper surface electrode layers constructed of silver-baseconductive powder containing glass for electrically connecting with thefirst upper surface electrode layers 22. A reference numeral 24represents a resistance layer having a chief component of rutheniumoxide for electrically connecting with the second upper surfaceelectrode layers 23. A reference numeral 25 is a protective layer havinga chief component of glass, provided on an upper surface of theresistance layer 24. Reference numerals 26 and 27 respectively representa nickel-plated layer and a solder-plated layer provided, as occasiondemands, for a purpose of assuring reliability, etc. during soldering.

The resistor of the first exemplary embodiment of this inventionconstructed as above is manufactured in a manner, which will bedescribed hereinafter by referring to the figures.

FIG. 2 and FIG. 3 represent a series of procedural views showing amanufacturing method of the resistor of the first exemplary embodimentof this invention.

First of all, first upper surface electrode layers 22 are formed, asshown in FIG. 2(a), by printing electrode paste containing gold-baseorganic metal in a manner to cross over slitting grooves 29 made in ahorizontal direction through a sheet-formed substrate 21, which has asuperior heat-resisting property and an insulating property as itcontains 96% alumina, and a surface of which is provided with aplurality of slitting grooves 28 and 29 in a vertical direction as wellas in a horizontal direction in order to separate it into rectangularstrips and then into individual pieces in the subsequent steps. Duringthis process, the electrode paste containing gold-base organic metalgets into the slitting grooves 29 of horizontal direction, so as to formthe first upper surface electrode layers 22 deeply down in the slittinggrooves. In addition, the first upper surface electrode layers 22 arecalcined at a temperature of approximately 850° C. in order to make thembecome secure films. Generally, the slitting grooves 28 and 29 are soformed that their depth with respect to a thickness of the substrate 21becomes equal to or less than a half of the thickness of the substrate21, so as to avoid it from being cracked during handling in themanufacturing process.

Next, electrode paste containing silver-base conductive powder and glassis printed to form second upper surface electrode layers 23 in a mannerthat each of them overlaps a portion of the first upper surfaceelectrode layers 22, as shown in FIG. 2(b). The second upper surfaceelectrode layers 23 are then calcined at a temperature of approximately850° C. in order to make them become stable films.

Resistive paste having a principal component of ruthenium oxide isprinted to form resistance layers 24 in a manner that they connectelectrically with the second upper surface electrode layers 23, as shownin FIG. 2(c). The resistance layers 24 are then calcined at atemperature of approximately 850° C. in order to make them become stablefilms.

Next, trimming is made to form trimmed slits 30 with a YAG laser, asshown in FIG. 3(a) in order to correct resistance values of theresistance layers 24 to a predetermined value. The trimming is made bysetting trimming probes for measuring a resistance value on the secondupper surface electrode layers 23 during this process.

Another paste having a principal component of glass is printed to formprotective layers 25, as shown in FIG. 3(b), in order to protect theresistance layers 24, of which resistance values have been corrected.For this process, a printing pattern may be made in such a shape thatthe protective layers 25 cross over the slitting grooves 28 of verticaldirection to connectively cover a plurality of the horizontally alignedresistance layers 24. The protective layers 25 are then calcined at atemperature of approximately 600° C. in order to make them become stablefilms.

Then, the substrate 21 in a sheet-form, on which the first upper surfaceelectrode layers 22, the second upper surface electrode layers 23, theresistance layers 24, the trimmed slits 30, and the protective layers 25have been formed, is separated into rectangular substrate strips 31 bysplitting it along the slitting grooves 29 of horizontal direction inthe substrate 21, as shown in FIG. 3(c). When this is done, thepreviously formed first upper surface electrode layers 22 lie in theirrespective positions on the side surfaces along a longitudinal directionof the rectangular substrate strips 31 down to the depth of the slittinggrooves 29 of horizontal direction.

As a preparatory process for plating exposed surfaces of the first uppersurface electrode layers 22 and the second upper surface electrodelayers 23, the rectangular substrate strips 31 are finally separatedinto individual substrate pieces 32 by splitting them along the slittinggrooves 28 of vertical direction, as shown in FIG. 3(d). A resistor isnow completed when a nickel-plated layer, as an intermediate layer (notshown in the figure), and a solder-plated layer, as an outer layer (notshown in the figure) are formed by means of electroplating on exposedsurfaces of the first upper surface electrode layers 22 and the secondupper surface electrode layers 23,in order to prevent electrode-erosionduring soldering and to assure reliability of the soldering.

The resistor of the first exemplary embodiment of this inventionconstructed and manufactured as above is soldered on a mount board. Asshown in a sectional view of FIG. 4(a) depicting the resistor of thefirst exemplary embodiment of this invention in a mounted position, theresistor is mounted with the surface having the protective layer down,and soldered with both the electrode layers on upper surfaces (not shownin the figure) and resistance layer portion on the side surface of thesubstrate. However, since these areas in the side surfaces, whereonelectrodes are formed, are so small that fillets 33 are barely formed.Accordingly, an actual mount area 36 comes to the sum of a componentarea 34 and areas 35 required for soldering the side surfaces, as shownin a plan view of FIG. 4(b) depicting the resistor of the firstexemplary embodiment of this invention in the mounted position. Theinvention attains a reduction of approximately 20% in the mount areawhen compared with a product of the prior art, in the case of asquare-tip resistor in a size of 0.6×0.3 mm.

Accordingly, the structure of this invention requires a small area on amount board to form fillets of soldering, because of the small areas ofelectrodes on the side surfaces of the resistor, and therefore it canreduce the mount areas.

In the first exemplary embodiment of this invention, if thesolder-plated layers 27 and the protective layer 25 are formed to be onthe same plane, or if the solder-plated layers 27 are formed to behigher than the protective layer 25, the resistor is not likely to allowa gap between the solder-plated layers 27 and a land pattern, when it ismounted, thereby further improving quality of mounting.

Besides, other characteristics can be improved in the first exemplaryembodiment of this invention, if the second upper surface electrodelayers 23 and the protective layer 25 are composed of combinations shownin Table 1.

TABLE 1 Second Combi- upper surface Protective Characteristics nationelectrode layers 23 layer 25 to be improved 1 Gold-base Glass-baseImprovement in loaded-life conductive powder material characteristic dueto low and glass (calcined (calcined at ion migration at 850° C.) 600°C.) 2 Silver-base Resin-base No variation in resistance conductivepowder material value in manufacturing and glass (calcined (hardened atprocess, and small at 850° C.) 200° C.) deviation in resistance value ofproducts, due to low processing temperature of protective layer. 3Gold-base Resin-base Both of characteristics of conductive powdermaterial above combinations and glass (calcined (hardened at 1 and 2. at850° C.) 200° C.)

In addition, it is easily conceivable that the mount area can be furtherreduced if electrodes are not formed on the side surfaces in the firstexemplary embodiment of this invention.

Second Exemplary Embodiment

A resistor of a second exemplary embodiment of the present invention anda method of manufacturing the same will be described hereinafter byreferring to accompanying figures.

FIG. 5 is a sectional view of a resistor of the second exemplaryembodiment of this invention.

In the figures, a reference numeral 41 represents a substrate containing96% of alumina. A reference numeral 42 represents first upper surfaceelectrode layers provided by sputtering gold-base material on sideportions of an upper surface toward portions of side surfaces of thesubstrate 41. Ridges of these first upper surface electrode layers 42are rounded. In addition, a surface area of the first upper surfaceelectrode layer 42 occupying the side surface of the substrate 41 is notmore than a half of an area of the side surface of the substrate 41. Areference numeral 43 represents second upper surface electrode layerscomposed of silver-base conductive powder containing glass for makingelectrical connection with the first upper surface electrode layers 42.A reference numeral 44 represents a resistance layer having a chiefcomponent of ruthenium oxide, for electrically connecting with thesecond upper surface electrode layers 43. A reference numeral 45 is aprotective layer having a chief component of glass, provided on an uppersurface of the resistance layer 44. Reference numerals 46 and 47respectively represent nickel-plated layers and solder-plated layersprovided, as occasion demands, for a purpose of assuring reliability,etc. during soldering.

The resistor of the second exemplary embodiment of this inventionconstructed as above is manufactured in a manner, which will bedescribed hereinafter by referring to the figures.

FIG. 6 and FIG. 7 represent a series of procedural views showing amanufacturing method of the resistor of the second exemplary embodimentof this invention.

First of all, gold is deposited in a form of film by sputtering methodon an entire upper surface of a sheet-formed substrate 41, which has asuperior heat-resisting property and an insulating property as itcontains 96% alumina, and a surface of which is provided with aplurality of slitting grooves 48 and 49 in a vertical direction as wellas in a horizontal direction in order to separate it into rectangularstrips and then into individual pieces in the subsequent steps. Further,first upper surface electrode layers 42 having a desired electrodepattern are formed, as shown in FIG. 6(a), by a photo-lithographicmethod which is commonly used for LSI's, and the like. The first uppersurface electrode layers 42 are then subjected to heat treatment at atemperature of approximately 300 to 400° C. in order to make them becomestable films. During this process, the first upper surface electrodelayers 42 get into slitting grooves 49 of horizontal direction, so as toform the first upper surface electrode layers 42 deeply down in theslitting grooves. Generally, the slitting grooves 48 and 49 are soformed that their depth with respect to a thickness of the substrate 41becomes equal to or less than a half of the thickness of the substrate41, so as to avoid it from being cracked during handling in themanufacturing process.

Next, electrode paste containing silver-base conductive powder and glassis printed to form second upper surface electrode layers 43 in a mannerto make electrical connections with the first upper surface electrodelayers 42, as shown in FIG. 6(b). The second upper surface electrodelayers 43 are then calcined at a temperature of approximately 850° C. inorder to make them become stable films.

Resistive paste having a principal component of ruthenium oxide isprinted to form resistance layers 44 in a manner that they connectelectrically with the second upper surface electrode layers 43, as shownin FIG. 6(c). The resistance layers 44 are then calcined at atemperature of approximately 850° C. in order to make them become stablefilms.

Next, trimming is made to form trimmed slits 50 with a YAG laser, asshown in FIG. 7(a) in order to correct resistance values of theresistance layers 44 to a predetermined value. The trimming is made withtrimming probes for measuring a resistance value set on the second uppersurface electrode layers 43 during this process.

Another paste having a principal component of glass is printed to formprotective layers 45, as shown in FIG. 7(b), in order to protect theresistance layers 44, of which resistance values have been corrected.For this process, a printing pattern may be made in such a shape thatthe protective layers 45 cross over the slitting grooves 48 of verticaldirection to connectively cover a plurality of the horizontally alignedresistance layers 44. The protective layers 45 are then calcined at atemperature of approximately 600° C. in order to make them become stablefilms.

Then, the substrate 41 in a sheet-form, on which the first upper surfaceelectrode layers 42, the second upper surface electrode layers 43, theresistance layers 44, the trimmed slits 50, and the protective layers 45have been formed, is separated into rectangular substrate strips 51 bysplitting it along the slitting grooves 49 of horizontal direction inthe substrate 41, as shown in FIG. 7(c). When this is done, thepreviously formed first upper surface electrode layers 42 lie in theirrespective positions on the side surfaces along a longitudinal directionof the rectangular substrate strips 51 down to the depth of the slittinggrooves 49 of horizontal direction.

As a preparatory process for plating exposed surfaces of the first uppersurface electrode layers 42 and the second upper surface electrodelayers 43, the rectangular substrate strips 51 are finally separatedinto individual substrate pieces 52 by splitting them along the slittinggrooves 48 of vertical direction, as shown in FIG. 7(d). A resistor isnow completed when a nickel-plated layer, as an intermediate layer (notshown in the figure), and a solder-plated layer, as an outer layer (notshown in the figure), are formed by means of electroplating on otherwiseexposed surfaces of the first upper surface electrode layers 42 and thesecond upper surface electrode layers 43 in order to preventelectrode-erosion during soldering and to assure reliability of thesoldering.

Distinctive effects of the resistor of the second exemplary embodimentof this invention constructed and manufactured as above, when it issoldered on a mount board, are same as in the case of the resistor ofthe foregoing first exemplary embodiment, and therefore they are notdescribed.

In addition, other characteristics can be improved in the secondexemplary embodiment of this invention, if the first upper surfaceelectrode layers 42, the second upper surface electrode layers 43, theresistance layer 44 and the protective layer 45 are composed ofcombinations shown in Table 2.

TABLE 2 First Second upper upper Com- surface surface ResistanceProtective bina- electrode electrode layer layer Characteristics to tionlayers 42 layers 43 44 45 be improved 4 Sputtered Gold-base RutheniumGlass-base Improvement in gold-base conductive oxide-base materialloaded-life char- material powder material (calcined acteristic due to(heat- and glass (calcined at 600° C.) low ion migration. treated at(calcined at 850° C.) 300- at 850° C.) 400° C.) 5 Sputtered Silver-baseRuthenium Resin-base No variation in gold-base conductive oxide-basematerial resistance value in material powder material (hardenedmanufacturing process, (heat- and glass (calcined at 200° C.) and smalldeviation in treated at (calcined at 850° C.) resistance value of 300-at 850° C.) products, due to low 400° C.) processing temperature ofprotective layer. 6 Sputtered Gold-base Ruthenium Resin-base Both ofcharacteristics gold-base conductive oxide-base material of abovecombinations 4 material powder material (hardened and 5. (heat- andglass (calcined at 200° C.) treated at (calcined at 850° C.) 300- at850° C.) 400° C.) 7 Sputtered Silver-base Carbonic Resin-base Samecharacteristic as nickel- conductive resin-base material abovecombination 5, base powder material (hardened with less manufacturingmaterial and resin (hardened at 200° C.) cost than above (heat-(hardened at 200° C.) combination 6 due to treated at at 200° C.) use ofbase metal for 300- first upper surface 400° C.) electrode layers. 8Sputtered Nickel- Carbonic Resin-base Same characteristic as nickel-base resin-base material above combination 7, base conductive material(hardened with less manufacturing material powder (hardened at 200° C.)cost than above (heat- and resin at 200° C.) combination 7 due totreated at (hardened use of base metal for 300- at 200° C.) second uppersurface 400° C.) electrode layers.

Third Exemplary Embodiment

A resistor of a third exemplary embodiment of the present invention anda method of manufacturing the same will be described hereinafter byreferring to accompanying figures.

FIG. 8 is a sectional view of a resistor of the third exemplaryembodiment of this invention.

In FIG. 8, a reference numeral 61 represents a substrate containing 96%of alumina. A reference numeral 62 represents first upper surfaceelectrode layers, which are constructed of calcined gold-base organicmetal compound, provided on side portions of an upper surface towardportions of side surfaces of the substrate 61. A surface area of thefirst upper surface electrode layer 62 occupying the side surface of thesubstrate 61 is not more than a half of an area of the side surface ofthe substrate 61. A reference numeral 63 represents a pair of secondupper surface electrode layers composed of silver-base conductive powdercontaining glass for making electrical connections with the first uppersurface electrode layers 62. A reference numeral 64 represents aresistance layer having a chief component of ruthenium oxide forelectrically connecting with the second upper surface electrode layers63. A reference numeral 65 is a protective layer having a chiefcomponent of glass provided on an upper surface of the resistance layer64. A reference numeral 66 represents third upper surface electrodelayers composed of silver-base conductive powder containing glass, andprovided on portions of upper surfaces of the second upper surfaceelectrode layers 63. Reference numerals 67 and 68 respectively representa nickel-plated layer and a solder-plated layer provided, as occasiondemands, for a purpose of assuring reliability, etc. during soldering.

The resistor of the third exemplary embodiment of this inventionconstructed as above is manufactured in a manner, which will bedescribed hereinafter by referring to the accompanying figures.

FIG. 9 through FIG. 11 represent a series of procedural views showing amanufacturing method of the resistor of the third exemplary embodimentof this invention.

In the beginning, first upper surface electrode layers 62 are formed, asshown in FIG. 9(a), by printing electrode paste containing gold-baseorganic metal compound in a manner to cross over slitting grooves 70made in a horizontal direction through a sheet-formed substrate 61,which has a superior heat-resisting property and an insulating propertyas it contains 96% alumina, and a surface of which is provided with aplurality of slitting grooves 69 and 70 in a vertical direction as wellas in a horizontal direction in order to separate it into rectangularstrips and then into individual pieces in the subsequent steps. Thefirst upper surface electrode layers 62 are subjected to calcination ata temperature of approximately 850° C. in order to make them becomestable films. During this process, the electrode paste gets into theslitting grooves 70 of horizontal direction, so as to form the firstupper surface electrode layers 62 deeply down in the slitting grooves.In general, the slitting grooves 69 and 70 are so formed that theirdepth with respect to a thickness of the substrate 61 becomes equal toor less than a half of the thickness of the substrate 61, in order toavoid it from being cracked during handling in the manufacturingprocess.

Next, electrode paste containing silver-base conductive powder and glassis printed to form second upper surface electrode layers 63 in a mannerto make electrical connections with the first upper surface electrodelayers 62, as shown in FIG. 9(b). The second upper surface electrodelayers 63 are then calcined at a temperature of approximately 850° C. inorder to make them become stable films.

Resistive paste having a principal component of ruthenium oxide isprinted to form resistance layers 64 in a manner that they connectelectrically with the second upper surface electrode layers 63, as shownin FIG. 9(c). The resistance layers 64 are then calcined at atemperature of approximately 850° C. in order to make them become stablefilms.

Next, trimming is made to form trimmed slits 71 with a YAG laser, asshown in FIG. 10(a) in order to correct resistance values of theresistance layers 64 to a predetermined value. The trimming is made withtrimming probes for measuring a resistance value set on the second uppersurface electrode layers 63 during this process.

Another paste having a principal component of glass is printed to formprotective layers 65, as shown in FIG. 10(b), in order to protect theresistance layers 64, of which resistance values have been corrected.For this process, a printing pattern may be made in such a shape thatthe protective layers 65 cross over the slitting grooves 69 of verticaldirection to connectively cover a plurality of the horizontally alignedresistance layers 64. The protective layers 65 are then calcined at atemperature of approximately 600° C. in order to make them become stablefilms.

Next, electrode paste containing silver-base conductive powder and glassis printed to form third upper surface electrode layers 66 on portionsof upper surfaces of the first upper surface electrode layers 62 and thesecond upper surface electrode layers 63 in a manner not to cross theslitting grooves 70 of horizontal direction, as shown in FIG. 10(c). Thethird upper surface electrode layers 66 are then calcined at atemperature of approximately 600° C. in order to make them become stablefilms.

Then, the substrate 61 in a sheet-form, on which the first upper surfaceelectrode layers 62, the second upper surface electrode layers 63, theresistance layers 64, the trimmed slits 71, the protective layers 65 andthe third upper surface electrode layers 66 have been formed, isseparated into rectangular substrate strips 72 by splitting it along theslitting grooves 70 of horizontal direction in the substrate 61, asshown in FIG. 11(a). When this is done, the previously formed firstupper surface electrode layers 62 lie in their respective positions onthe side surfaces along a longitudinal direction of the rectangularsubstrate strips 72 down to the depth of the slitting grooves 70 ofhorizontal direction.

As a preparatory process for plating exposed surfaces of the first uppersurface electrode layers 62, the second upper surface electrode layers63 and the third upper surface electrode layers 66, the rectangularsubstrate strips 72 are finally separated into individual substratepieces 73 by splitting them along the slitting grooves 69 of vertical,direction, as shown in FIG. 11(b). A resistor is now completed when anickel-plated layer, as an intermediate layer (not shown in the figure),and a solder-plated layer, as an outer layer (not shown in the figure)are formed by means of electroplating on all exposed surfaces of thefirst upper surface electrode layers 62, the second upper surfaceelectrode layers 63 and the third upper surface electrode layers 66 inorder to prevent electrode-erosion during soldering, and to assurereliability of the soldering.

The resistor of the third exemplary embodiment of this inventionconstructed and manufactured as above is soldered on a mount board. Theresistor is mounted with the surface having the protective layer down,as shown in a sectional view of FIG. 12(a) depicting a mounted positionin the third exemplary embodiment of this invention, and soldered withthe first, second and third upper surface electrode layers (not shown inthe figure) and the resistance layer portion on a side surface of thesubstrate. However, since these areas in the side surfaces, whereon theelectrodes are formed, are so small that fillets 74 are barely formed.Accordingly, an actual mount area 77 comes to the sum of a componentarea 75 and areas 76 required for soldering the side surfaces of thiscomponent, as shown in a plan view of FIG. 12(b) depicting the mountedposition. The invention attains a reduction of approximately 20% in themount area when compared with a product of the prior art, in the case ofa square-tip resistor in a size of 0.6×0.3 mm.

Therefore, the structure according to the third exemplary embodiment ofthis invention requires a small area on a mount board to form fillets ofsoldering, because of the small areas of electrodes on the side surfacesof the resistor, and thereby it can reduce the mount areas.

In the third exemplary embodiment of this invention, if solder-platedlayers 68 and the protective layer 65 are formed to be on the sameplane, or if the solder-plated layers 68 are formed to be higher thanthe protective layer 65, the resistor is not likely to allow a gapbetween the solder-plated layers 68 and a land pattern 76, when it ismounted, thereby further improving quality of mounting.

Besides, other characteristics can be improved in the third exemplaryembodiment of this invention, if the second upper surface electrodelayers 63, the protective layer 65 and the third upper surface electrodelayers 66 are composed of combinations shown in Table 3.

TABLE 3 Second upper Third upper Com- surface surface Protective bina-electrode electrode layer Characteristics to be tion layers 63 layers 6665 improved 1 Silver-base Silver-base Glass-base No variation inresistance conductive conductive material value during manufact- powderand powder and (calcined uring process, and small glass resin atdeviation in resistance (calcined at (hardened at 600° C.) value ofproducts, due to 850° C.) 200° C.) low processing temper- ature of thirdupper surface electrode layers 66. 2 Silver-base Nickel-base Glass-baseSame characteristic as conductive conductive material above combination1, powder powder and (calcined with less manufacturing (calcined atresin at cost due to use of base 850° C.) (hardened at 600° C.) metalfor third upper 200° C.) surface electrode layers 66. 3 Silver-baseSilver-base Resin-base Small deviation in re- conductive conductivematerial sistance value of pro- powder and powder and (hardened ducts,due to less glass resin at variation in manufact- (calcined at (hardenedat 200° C.) uring process than above 850° C.) 200° C.) combination 1, asprotective layer 65 is processed at lower temperature 4 Silver-baseNickel-base Resin-base Same characteristic as conductive conductivematerial above combination 3, powder and powder and (hardened with lessmanufact- glass resin at uring cost due to use of (calcined at (hardenedat 200° C.) base metal for third 850° C.) 200° C.) upper surfaceelectrode layers 66. 5 Gold-base Silver-base Glass-base Improvement inloaded- conductive conductive material life characteristic due to powderand powder and (calcined low ion migration. glass glass at (calcined at(calcined at 600° C.) 850° C.) 600° C.) 6 Gold-base Silver-baseGlass-base Both of characteristics of conductive conductive materialabove combinations powder and powder and (calcined 1 and 5. glass resinat (calcined at (hardened at 600° C.) 850° C.) 200° C.) 7 Gold-baseNickel-base Glass-base Both of characteristics of conductive conductivematerial above combinations powder and powder and (calcined 2 and 5.glass resin at (calcined at (hardened at 600° C.) 850° C.) 200° C.) 8Gold-base Silver-base Resin-base Both of characteristics of conductiveconductive material above combinations powder and powder and (hardened 3and 5. glass resin at (calcined at (hardened at 200° C.) 850° C.) 200°C.) 9 Gold-base Nickel-base Resin-base Both of characteristics ofconductive conductive material above combinations powder and powder and(hardened 4 and 5. glass resin at (calcined at (hardened at 200° C.)850° C.) 200° C.)

In addition, it is easily conceivable that the mount area can be furtherreduced if electrodes are not formed on the side surfaces in the thirdexemplary embodiment of this invention.

Fourth Exemplary Embodiment

A resistor of a fourth exemplary embodiment of the present invention anda method of manufacturing the same will be described hereinafter byreferring to accompanying figures.

FIG. 13 is a sectional view of a resistor of the fourth exemplaryembodiment of this invention.

In FIG. 13, a reference numeral 81 represents a substrate containing 96%of alumina. A reference numeral 82 represents first upper surfaceelectrode layers provided by sputtering gold-base material on sideportions of an upper surface and portions of side surfaces of thesubstrate 81. A surface area of the first upper surface electrode layer82 occupying the side surface of the substrate 81 is not more than ahalf of an area of the side surface of the substrate 81. A referencenumeral 83 represents second upper surface electrode layers containingsilver-base conductive powder and glass for making electricalconnections with the first upper surface electrode layers 82. Areference numeral 84 represents a resistance layer having a chiefcomponent of ruthenium oxide for electrically connecting with the secondupper surface electrode layers 83. A reference numeral 85 is aprotective layer having a chief component of glass, and provided on anupper surface of the resistance layer 84. A reference numeral 86represents third upper surface electrode layers composed of silver-baseconductive powder containing glass, provided on portions of the firstupper surface electrode layers 82 and the second upper surface electrodelayers 83. Reference numerals 87 and 88 respectively representnickel-plated layers and solder-plated layers provided, as occasiondemands, for a purpose of assuring reliability, etc. during soldering.

The resistor of the fourth exemplary embodiment of this inventionconstructed as above is manufactured in a manner, which will bedescribed hereinafter by referring to the figures.

FIG. 14 through FIG. 16 represent a series of procedural views showing amanufacturing method of the resistor of the fourth exemplary embodimentof this invention.

First of all, gold is deposited in a form of film by sputtering methodon an entire upper surface of a sheet-formed substrate 81, which has asuperior heat-resisting property and an insulating property as itcontains 96% alumina, and a surface of which is provided with aplurality of slitting grooves 89 and 90 in a vertical direction as wellas a horizontal direction in order to separate it into rectangularstrips and individual pieces in the subsequent steps. Further, firstupper surface electrode layers 82 having a desired electrode pattern areformed, as shown in FIG. 14(a), by photo-lithographic method which isnormally used for LSI's, and the like. The first upper surface electrodelayers 82 are subjected to heat treatment at a temperature ofapproximately 300 to 400° C. in order to make them become stable films.During this process, the first upper surface electrode layers 82 getinto the slitting grooves 90 of horizontal direction, so as to form thefirst upper surface electrode layers 82 deeply down in the slittinggrooves. Generally, the slitting grooves 89 and 90 are so formed thattheir depth with respect to a thickness of the substrate 81 becomesequal to or less than a half of the thickness of the substrate 81, so asto avoid it from being cracked during handling in the manufacturingprocess.

Next, electrode paste containing silver-base conductive powder and glassis printed to form second upper surface electrode layers 83 in a mannerto make electrical connections with the first upper surface electrodelayers 82, as shown in FIG. 14(b). The second upper surface electrodelayers 83 are then calcined at a temperature of approximately 850° C. inorder to make them become stable films.

Resistive paste having a principal component of ruthenium oxide isprinted to form resistance layers 84 in a manner that they connectelectrically with the second upper surface electrode layers 83, as shownin FIG. 14(c). The resistance layers 84 are then calcined at atemperature of approximately 850° C. in order to make them become stablefilms.

Next, trimming is made to form trimmed slits 91 with a YAG laser, asshown in FIG. 15(a) in order to correct resistance values of theresistance layers 84 to a predetermined value. The trimming is made withtrimming probes for measuring a resistance value set on the second uppersurface electrode layers 83 during this process.

Another paste having a principal component of glass is printed to formprotective layers 85, as shown in FIG. 15(b), in order to protect theresistance layers 84, of which resistance values have been corrected.For this process, a printing pattern may be made in such a shape thatthe protective layers 85 cross over the slitting grooves 89 of verticaldirection to connectively cover a plurality of the horizontally alignedresistance layers 84. The protective layers 85 are then calcined at atemperature of approximately 600° C. in order to make them become stablefilms.

Next, electrode paste containing silver-base conductive powder and glassis printed to form third upper surface electrode layers 86 on portionsof upper surfaces of the first upper surface electrode layers 82 and thesecond upper surface electrode layers 83 in a manner not to cross theslitting grooves 90 of horizontal direction, as shown in FIG. 15(c). Thethird upper surface electrode layers 86 are then calcined at atemperature of approximately 600° C. in order to make them become stablefilms.

Then, the substrate 81 in a sheet-form, on which the first upper surfaceelectrode layers 82, the second upper surface electrode layers 83, theresistance layers 84, the trimmed slits 91, the protective layers 85 andthe third upper surface electrode layers 86 have been formed, isseparated into rectangular substrate strips 92 by splitting it along theslitting grooves 90 of horizontal direction in the substrate 81, asshown in FIG. 16(a). When this is done, the previously formed firstupper surface electrode layers 82 lie in their respective positions onthe side surfaces along a longitudinal direction of the rectangularsubstrate strips 92 down to the depth of the slitting grooves 90 ofhorizontal direction.

As a preparatory process for plating exposed surfaces of the first uppersurface electrode layers 82, the second upper surface electrode layers83 and the third upper surface electrode layers 86, the rectangularsubstrate strips 82 are finally separated into individual substratepieces 93 by splitting them along the slitting grooves 89 of verticaldirection, as shown in FIG. 16(b). A resistor is now completed when anickel-plated layer, as an intermediate layer (not shown in the figure),and a solder-plated layer, as an outer layer (not shown in the figure)are formed by means of electroplating on all exposed surfaces of thefirst upper surface electrode layers 82, the second upper surfaceelectrode layers 83 and the third upper surface electrode layers 86 inorder to prevent electrode-erosion during soldering, and to assurereliability of the soldering.

Distinctive effects of the resistor of the fourth exemplary embodimentof this invention constructed and manufactured as above, when it issoldered on a mount board, are same as in the case of theabove-described third exemplary embodiment, and therefore they are notdescribed further.

In addition, other characteristics can be improved in the fourthexemplary embodiment of this invention, if the first upper surfaceelectrode layers 82, the second upper surface electrode layers. 83, theresistance layer 84, the protective layer 85 and the third upper surfaceelectrode layers 86 are composed of combinations shown in Table 4.

TABLE 4 Second First upper upper Third upper Resistance Com- surfacesurface surface layer 84 bina- electrode electrode electrode ProtectiveCharacteristics to be tion layers 82 layers 83 layers 86 layer 85improved 10 Sputtered Silver-base Silver-base Ruthenium Samecharacteristic gold-base conductive conductive oxide-base as combination1 in material powder and powder and (calcined at Table 1. glass glass850° C.) (calcined at (hardened Glass-base 850° C.) at 200° C.)(calcined at 600° C.) 11 Sputtered Silver-base Nickel-base RutheniumSame characteristic gold-base conductive conductive oxide-base ascombination 2 in material powder and powder and (calcined at Table 1.glass resin 850° C.) (calcined at (hardened Glass-base 850° C.) at 200°C.) (calcined at 600° C.) 12 Sputtered Silver-base Silver-base RutheniumSame characteristic gold-base conductive conductive oxide-base ascombination 3 in material powder and powder and (calcined at Table 1.glass resin 850° C.) (calcined at (hardened Resin-base 850° C.) at 200°C.) (hardened at 200° C.) 13 Sputtered Silver-base Nickel-base RutheniumSame characteristic gold-base conductive conductive oxide-base ascombination 4 in material powder and powder and (calcined at Table 1.glass resin 850° C.) (calcined at (hardened Resin-base 850° C.) at 200°C.) (hardened at 200° C.) 14 Sputtered Gold-base Silver-base RutheniumSame characteristic gold-base conductive conductive oxide-base ascombination 5 in material powder and powder and (calcined at Table 1.glass glass 850° C.) (calcined at (calcined at Glass-base 850° C.) 600°C.) (calcined at 600° C.) 15 Sputtered Gold-base Silver-base RutheniumSame characteristic gold-base conductive conductive oxide-base ascombination 6 in material powder and powder and (calcined at Table 1.glass resin 850° C.) (calcined at (hardened Glass-base 850° C.) at 200°C.) (calcined at 600° C.) 16 Sputtered Gold-base Nickel-base RutheniumSame characteristic gold-base conductive conductive oxide-base ascombination 7 in material powder and powder and (calcined at Table 1.glass resin 850° C.) (calcined at (hardened Glass-base 850° C.) at 200°C.) (calcined at 600° C.) 17 Sputtered Gold-base Silver-base RutheniumSame characteristic gold-base conductive conductive oxide-base ascombination 8 in material powder and powder and (calcined at Table 1.glass resin 850° C.) (calcined at (hardened Resin-base 850° C.) at 200°C.) (hardened at 200° C.) 18 Sputtered Gold-base Nickel-base RutheniumSame characteristic gold-base conductive conductive oxide-base ascombination 9 in material powder and powder and (calcined at Table 1.glass resin 850° C.) (calcined at (hardened Resin-base 850° C.) at 200°C.) (hardened at 200° C.) 19 Sputtered Silver-base Silver-base CarbonicSave electricity, as nickel-base conductive conductive resin-basematerial needing low material powder and powder and (hardened tempprocessing is resin resin at 200° C.) used for second upper (hardened(hardened Resin-base surface electrode at 200° C.) at 200° C.) (hardenedlayers 83 and at 200° C.) resistance layer 84. 20 Sputtered Silver-baseNickel-base Carbonic Same characteristic nickel-base conductiveconductive resin-base as combination 19, material powder and powder and(hardened with less resin resin at 200° C.) manufacturing cost (hardened(hardened Resin-base due to use of base at 200° C.) at 200° C.)(hardened metal for third upper at 200° C.) surface electrode layers 86.

In addition, it is easily conceivable that the mount area can be furtherreduced if electrodes are not formed on the side surfaces in the fourthexemplary embodiment of this invention.

Fifth Exemplary Embodiment

A resistor of a fifth exemplary embodiment of the present invention anda method of manufacturing the same will be described hereinafter byreferring to accompanying figures.

FIG. 17 is a sectional view of a resistor of the fifth exemplaryembodiment of this invention.

In FIG. 17, a reference numeral 101 represents a substrate containing96% of alumina. A reference numeral 102 represents first upper surfaceelectrode layers composed of silver-base conductive powder containingglass, and provided on side portions of a main surface of the substrate101. A reference numeral 103 represents a resistance layer having achief component of ruthenium oxide for electrically connecting with thefirst upper surface electrode layers 102. A reference numeral 104 is aprotective layer having a chief component of glass, and provided on anupper surface of the resistance layer 103. A reference numeral 105represents second upper surface electrode layers formed by means ofsputtering gold-base material on upper surfaces and portions of sidesurfaces of the first upper surface electrode layers 102. A surface areaof the second upper surface electrode layer 105 occupying the sidesurface of the substrate 101 is mot more than a half of an area of theside surface of the substrate 101. A reference numeral 106 representsthird upper surface electrode layers composed of silver-base conductivepowder containing glass, overlapping portions of upper surfaces of thefirst upper surface electrode layers 102 and the second upper surfaceelectrode layers 105. Reference numerals 107 and 108 respectivelyrepresent nickel-plated layers and solder-plated layers provided, asoccasion demands, for a purpose of assuring reliability, etc. duringsoldering.

The resistor of the fifth exemplary embodiment of this inventionconstructed as above is manufactured in a manner, which will bedescribed hereinafter by referring to the figures.

FIG. 18 through FIG. 20 represent a series of procedural views showing amanufacturing method of the resistor of the fifth exemplary embodimentof this invention.

First of all, electrode paste containing silver-base conductive powderand glass is printed to form first upper surface electrode layers 102,as shown in FIG. 18(a), in a manner not to cross over slitting grooves110 made in a horizontal direction through a sheet-formed substrate 101,which has a superior heat-resisting property and an insulating propertyas it contains 96% alumina, and a surface of which is provided with aplurality of slitting grooves 109 and 110 in a vertical direction aswell as in a horizontal direction in order to separate it intorectangular strips and then into individual pieces in the subsequentsteps.

Next, resistive paste having a principal component of ruthenium oxide isprinted to form resistance layers 103 in a manner that they connectelectrically with the first upper surface electrode layers 102, as shownin FIG. 18(b). The resistance layers 103 are then calcined at atemperature of approximately 850° C. in order to make them become stablefilms.

Next, trimming is made to form trimmed slits 111 with a YAG laser, asshown in FIG. 18(c) in order to correct resistance values of theresistance layers 103 to a predetermined value. The trimming is madewith trimming probes for measuring a resistance value set on the firstupper surface electrode layers 102 during this process.

Another paste having a principal component of glass is printed to formprotective layers 104, as shown in FIG. 19(a), in order to protect theresistance layers 103, of which resistance values have been corrected.For this process, a printing pattern may be made in such a shape thatthe protective layers 104 cross over the slitting grooves 109 ofvertical direction to connectively cover a plurality of the horizontallyaligned resistance layers 103. The protective layers 104 are thencalcined at a temperature of approximately 600° C. in order to make thembecome stable films.

Resist material composed of resin is coated over an entire upper surfaceof the substrate 101, and openings in a film-forming pattern of thedesired second upper surface electrode layers 105 are prepared in theresist material by photo-lithographic method, as shown in FIG. 19(b).Furthermore, a gold is deposited in a form of film on the entire uppersurface of the substrate by sputtering method, and the resist materialis then removed except for portions of the film-forming pattern for thedesired second upper surface electrode layers 105. These steps completethe second upper surface electrode layers 105. During the above process,the second upper surface electrode layers 105 get into the slittinggrooves 110 of horizontal direction, and thereby the second uppersurface electrode layers 105 can be formed deeply down to the deep inthe slitting grooves.

Generally, the slitting grooves 109 and 110 are so formed that theirdepth with respect to a thickness of the substrate 101 becomes equal toor less than a half of the thickness of the substrate 101, so as toavoid it from being cracked during handling in the manufacturingprocess.

Next, electrode paste containing silver-base conductive powder and glassis printed to form third upper surface electrode layers 106 in a mannerto overlap with portions of upper surfaces of the first upper surfaceelectrode layers 102 and the second upper surface electrode layers 105,as shown in FIG. 19(c). The third upper surface electrode layers 106 arethen calcined at a temperature of approximately 850° C. in order to makethem become stable films.

Then, the substrate 101 in a sheet-form, on which the first uppersurface electrode layers 102, the second upper surface electrode layers105, the third upper surface electrode layers 106, the resistance layers103, the trimmed slits 111 and the protective layers 104 have beenformed, is separated into rectangular substrate strips 112 by splittingit along the slitting grooves 110 of horizontal direction in thesubstrate 101, as shown in FIG. 20(a). When this is done, the previouslyformed second upper surface electrode layers 105 lie in their respectivepositions on the side surfaces along a longitudinal direction of therectangular substrate strips 112 down to the depth of the slittinggrooves 110 of horizontal direction.

As a preparatory process for plating exposed surfaces of the first uppersurface electrode layers 102, the second upper surface electrode layers105 and the third upper surface electrode layers 106, the rectangularsubstrate strips 112 are finally separated into individual substratepieces 113 by splitting them along the slitting grooves 109 of verticaldirection, as shown in FIG. 20(b). A resistor is now completed when anickel-plated layer, as an intermediate layer (not shown in the figure),and a solder-plated layer, as an outer layer (not shown in the figure),are formed by means of electroplating on all exposed surfaces of thefirst upper surface electrode layers 102, the second upper surfaceelectrode layers 105 and the third upper surface electrode layers 106 inorder to prevent electrode-erosion during soldering and to assurereliability of the soldering.

Distinctive effects of the resistor of the fifth exemplary embodiment ofthis invention constructed and manufactured as above, when it issoldered on a mount board, are same as in the case of the foregoingthird exemplary embodiment, and therefore they are not described.

In addition, other characteristics can be improved in this fifthexemplary embodiment of the invention, if the first upper surfaceelectrode layers 102, the resistance layer 103, the protective layer104, the second upper surface electrode layers 105, and the third uppersurface electrode layers 106 are composed of combinations shown in Table5.

TABLE 5 Second upper First upper Third upper Resistance Com- surfacesurface surface layer 103 bina- electrode electrode electrode ProtectiveCharacteristics to be tion layers 105 layers 102 layers 106 layer 104improved 21 Sputtered Silver-base Silver-base Ruthenium Samecharacteristic gold-base conductive conductive oxide-base as combination1 in material powder and powder and (calcined at Table 1. glass resin850° C.) (calcined at (hardened Glass-base 850° C.) at 200° C.)(calcined at 600° C.) 22 Sputtered Silver-base Nickel-base RutheniumSame characteristic gold-base conductive conductive oxide-base ascombination 2 in material powder and powder and (calcined at Table 1.glass resin 850° C.) (calcined at (hardened Glass-base 850° C.) at 200°C.) (calcined at 600° C.) 23 Sputtered Silver-base Silver-base RutheniumSame characteristic gold-base conductive conductive oxide-base ascombination 3 in material powder and powder and (calcined at Table 1.glass resin 850° C.) (calcined at (hardened Resin-base 850° C.) at 200°C.) (hardened at 200° C.) 24 Sputtered Silver-base Nickel-base RutheniumSame characteristic gold-base conductive conductive oxide-base ascombination 4 in material powder and powder and (calcined at Table 1.glass resin 850° C.) (calcined at (hardened Resin-base 850° C.) at 200°C.) (hardened at 200° C.) 25 Sputtered Silver-base Silver-base RutheniumSame characteristic nickel-base conductive conductive oxide-base ascombination 23, material powder and powder and (calcined at with lessglass resin 850° C.) manufacturing cost (calcined at (hardened atResin-base due to use of base 850° C.) 200° C.) (hardened at metal forsecond 200° C.) upper surface electrode layers 105. 26 SputteredSilver-base Nickel-base Ruthenium Same characteristic nickel-baseconductive conductive oxide-base as combination 25, material powder andpowder and (calcined at with less glass resin 850° C.) manufacturingcost (calcined at (hardened Resin-base due to use of base 850° C.) at200° C.) (hardened at metal for third upper 200° C.) surface electrodelayers 106. 27 Sputtered Gold-base Silver-base Ruthenium Samecharacteristic gold-base conductive conductive oxide-base as combination5 in material powder and powder and (calcined at Table 1. glass glass850° C.) (calcined at (calcined at Glass-base 850° C.) at 600° C.)(calcined at 600° C.) 28 Sputtered Gold-base Silver-base Ruthenium Samecharacteristic gold-base conductive conductive oxide-base as combination6 in material powder and powder and (calcined at Table 1. glass resin850° C.) (calcined at (hardened Glass-base 850° C.) at 200° C.)(calcined at 600° C.) 29 Sputtered Gold-base Nickel-base Ruthenium Samecharacteristic gold-base conductive conductive oxide-base as combination7 in material powder and powder and (calcined at Table 1. glass resin850° C.) (calcined at (hardened Glass-base 850° C.) at 200° C.)(calcined at 600° C.) 30 Sputtered Gold-base Silver-base Ruthenium Savecharacteristic gold-base conductive conductive oxide-base as combination8 in material powder and powder and (calcined Table 1. glass resin at200° C.) (calcined (hardened Resin-base at 850° C.) at 200° C.)(hardened at 200° C.) 31 Sputtered Gold-base Nickel-base Ruthenium Samecharacteristic gold-base conductive conductive oxide-base as combination9 in material powder and powder and (calcined Table 1. glass resin at200° C.) (calcined (hardened Resin-base at 850° C.) at 200° C.)(hardened at 200° C.) 32 Sputtered Gold-base Silver-base Ruthenium Samecharacteristics nickel-base conductive conductive oxide-base ascombination 25 as material powder and powder and (calcined at well ascombination glass resin 850° C.) 5 in Table 1. (calcined at (hardenedResin-base 850° C.) at 200° C.) (hardened at 200° C.) 33 SputteredSilver-base Nickel-base Ruthenium Same characteristic nickel-baseconductive conductive oxide-base as combination 26 as material powderand powder and (calcined at well as combination glass resin 850° C.) 5in Table 1. (calcined at (hardened Resin-base 850° C.) at 200° C.)(hardened at 200° C.)

In addition, it is easily conceivable that the mount area can be furtherreduced if electrodes are not formed on the side surfaces in the fifthexemplary embodiment of this invention.

Sixth Exemplary Embodiment

A resistor of a sixth exemplary embodiment of the present invention anda method of manufacturing the same will be described hereinafter byreferring to accompanying figures.

FIG. 21 is a sectional view of a resistor of the sixth exemplaryembodiment of this invention.

In FIG. 21, a reference numeral 121 represents a substrate containing96% of alumina. A reference numeral 122 represents a pair of uppersurface electrode layers composed of thin films of gold-base materialprovided on sides portions of a main surface of the substrate 121. Areference numeral 123 represents a resistance layer composed of a thinfilm of nickel-chrome base or chrome-silicon base compound provided onan upper surface of the substrate 121. A reference numeral 124 is aprotective layer composed of epoxy-group resin, or the like materialprovided on an upper surface of the resistance layer 123. A referencenumeral 125 represents side surface electrode layers composed of thinfilms of nickel-base material provided on side surfaces of the substrate121. Reference numerals 126 and 127 respectively represent nickel-platedlayers and solder-plated layers provided, as occasion demands, for apurpose of assuring reliability, etc. during soldering. Ridges of thesenickel-plated layers 126 and solder-plated layers 127 are rounded. Eachsurface area of the solder-plated layers 127 occupying the side surfaceof the substrate 121 is not more than a half of an area of the sidesurface of the substrate 121.

The resistor of the sixth exemplary embodiment of this inventionconstructed as above is manufactured in a manner, which will bedescribed hereinafter by referring to the figures.

FIG. 22 through FIG. 24 represent a series of procedural views showing amanufacturing method of the resistor of the sixth exemplary embodimentof this invention.

First of all, electrode paste consisting of metallic-organic substance,etc. having a principal component of gold and the like material isscreen-printed in a manner not to cross over slitting grooves 129 madein a horizontal direction through an upper surface of sheet-formedsubstrate 121, which has a superior heat-resisting property and aninsulating property as it contains 96% alumina, and a surface of whichis provided with a plurality of slitting grooves 128 and 129 in avertical direction as well as in a horizontal direction in order toseparate it into rectangular strips and then into individual pieces inthe subsequent steps. After the electrode paste consisting ofmetallic-organic substance and the like is dried, it is calcined under acondition of approximately 850° C. for about 45 minutes in abelt-conveyed continuous kiln in order to disperse only organiccomponents and to bake only metal components of the electrode paste ontothe substrate 121, to form upper surface electrode layers 122 in thinfilm, as shown in FIG. 22(a).

Next, as shown in FIG. 22(b), nickel-chrome, chrome-silicon, or the likecompound is deposited by sputtering method on an entire upper surface ofthe sheet-formed substrate 121, on which the upper surface electrodelayers 122 (not shown in this figure) are formed, to form an integralresistance layer 130.

The integral resistance layer 130 is then processed byphoto-lithographic method, the same method as normally used for LSI's,etc. to form resistance layers 123 of a desired pattern, as shown inFIG. 22(c). The resistance layers 123 are thermally treated at atemperature of approximately 300 to 400° C. in order to make them becomestable films.

Next, trimming is made to form trimmed slits 131 with a YAG laser, asshown in FIG. 23(a) in order to correct resistance values of theresistance layers 123 to a predetermined value. Trimming probes formeasuring a resistance value are set on the upper surface electrodelayers 122 in this process. The trimming is made by serpentine cuttingmethod (a plurality of straight cuts), which is capable of adjusting theresistance freely from a low value to a high value.

Epoxy-base resin paste is screen-printed to form a printing pattern ofindividual protective layers corresponding to their respectiveresistance layers 123, as shown in FIG. 23(b), in order to protect theresistance layers 123, of which resistance values have been corrected.Then, the epoxy-base resin paste is thermally set to form the protectivelayers 124 under a condition of approximately 200° C. for about 30minutes in a belt-conveyed continuous hardening kiln in order to ensurea firm adhesion to the substrate 121. For this process, the printingpattern of the protective layers may be made in such a shape that theprotective layers cross over the slitting grooves 128 of verticaldirection, and connectively cover a plurality of the horizontallyaligned resistance layers 123.

Subsequently, as shown in the same figure, side surface electrode layers125 comprising a thin film of nickel-chrome base compound are formed bysputtering in a manner to cross over the slitting grooves 129 ofhorizontal direction, and to electrically connect with the upper surfaceelectrode layers 122. In this process, a resist layer is formed inadvance in an area other than portions where the side surface electrodelayers are formed. After a nickel-chrome layer is formed by sputteringover an entire surface of the substrate, the nickel-chrome layer of thearea other than the side surface electrode layers is removed at the sametime the resist layer is removed by lift-off method.

Then, the substrate 121 in a sheet-form is subjected to a primaryseparation into rectangular substrate strips 132, as shown in FIG.24(a), by splitting it along the slitting grooves 129 of horizontaldirection in the substrate 121. When this is done, the side surfaceelectrode layers 125 lie in their respective positions on the sidesurfaces along a longitudinal direction of the rectangular substratestrips 132 down to the depth of the slitting grooves 129 of horizontaldirection.

Finally, as a preparatory process for plating exposed surfaces of theupper surface electrode layers 122 and the side surface electrode layers125, a secondary separation is made to separate the rectangularsubstrate strips 132 into individual substrate pieces 133, as shown inFIG. 24(b). A resistor is now completed when a nickel-plated layer, asan intermediate layer (not shown in the figure), and a solder-platedlayer, as an outer layer (not shown in the figure), are formed by meansof electroplating on exposed surfaces of the upper surface electrodelayers 122 and the side surface electrode layers 125, if necessary inorder to prevent electrode-erosion during soldering and to assurereliability of the soldering.

The resistor of the sixth exemplary embodiment of this inventionconstructed and manufactured as above was soldered on a mount board. Theresistor was mounted with the surface having the protective layer down,and soldered with both the upper surface electrode layers (not shown inthe figure) and the resistance layer portion on side surface of thesubstrate, as shown in a sectional view of FIG. 25(a) depicting themounted position. However, since areas, whereon the side surfaceelectrodes are formed, were so small, fillets 134 were barely formed.Accordingly, an actual mount area 137 came to the sum of a componentarea 135 and areas 136 required for soldering the side surfaces, asshown in a plan view of FIG. 25(b) depicting the mounted position. Theinvention could attain a reduction of approximately 20% in the mountarea as compared to a product of the prior art, in the case of asquare-tip resistor in a size of 0.6×0.3 mm.

Therefore, the structure according to the present invention requires asmall area on a mount board to form fillets of soldering, because of thesmall areas of the side surface electrodes of the resistor, and therebyit can reduce the mount areas.

Moreover, the side surface electrode layers 125 formed by sputtering canprovide such advantages as strong adhesion to the substrate, realizing alinearity in boundary lines between the substrate 121 and thesolder-plated layers 127 on the side surfaces of the substrate 121, andhigh quality of the external appearance.

In addition, it is easily conceivable that the mount area can be furtherreduced if the side surface electrode layers 125 are not formed in thesixth exemplary embodiment of this invention. However, if the sidesurface electrode layers 125 are not formed, the resistor forms nofillet at all, thereby giving rise to a problem that makes an automatedinspection by image recognition inexecutable, in consideration of thefact that inspection of soldering is usually carried out by means ofimage recognition after mounting components in the current manufacturingprocess of electronic devices.

In the sixth exemplary embodiment of this invention, if solder-platedlayers 127 and the protective layer 124 are formed to be on the sameplane, or if the solder-plated layers 127 are formed to be higher thanthe protective layer 124, the resistor is not likely to allow a gapbetween the solder-plated layers 127 and a land pattern, when it ismounted, thereby further improving quality of mounting.

Furthermore, similar effect can be attained with other combinations ofthe upper surface electrode layers 122, the resistance layer 123 and theprotective layer 124, beside the above combination in the structure ofthe sixth exemplary embodiment of this invention. These combinations andtheir respective characteristics are outlined in Table 6.

TABLE 6 Com- Upper surface Resistance Protective bina- electrode layerslayer layer tion 122 123 124 Characteristics 1 Silver or gold-baseRuthenium Resin-base High accuracy in resistance conductive powderoxide-base material value due to low forming and glass material(hardened temperature of protective (calcined at (calcined at at 200°C.) layer. 850° C.) 850° C.) 2 Silver or gold-base Ruthenium Glass-baseHigh resistance to humidity conductive powder oxide-base material due toprotective layer and glass material (calcined at composed of glass.(calcined at (calcined at 600° C.) 850° C.) 850° C.) 3 Silver orgold-base Carbonic Resin-base Capable of saving energy conductive powderresin-base material due to low forming and glass material (hardenedtemperature of resistance (calcined at (hardened at 200° C.) layer, inaddition to 850° C.) at 200° C.) characteristic of combination 1. 4Silver or gold-base Ni-Cr base Resin-base Same characteristic asconductive powder or Cr-Si material combination 1. and glass base(hardened (calcined at sputtered at 200° C.) 850° C.) film 5. Gold-baseorganic Ruthenium Resin-base Low manufacturing cost metal compoundoxide-base material due to small amount of (calcined at material(hardened gold used, in addition to 850° C.) (calcined at at 200° C.)characteristic of 850° C.) combination 1. 6 Gold-base organic RutheniumGlass-base Low manufacturing cost metal compound oxide-base material dueto small amount of (calcined at material (calcined at gold used, inaddition to 850° C.) (calcined at 600° C.) characteristic of 850° C.)combination 2 7 Gold-base organic Carbonic Resin-base Low manufacturingcost metal compound resin-base material due to small amount of (calcinedat material (hardened gold used, in addition to 850° C.) (hardened at200° C.) characteristic of at 200° C.) combination 3 8 Gold-base organicNi-Cr base Resin-base (Combination of the first metal compound or Cr-Simaterial exemplary embodiment) (calcined at base (hardened 850° C.)sputtered at 200° C.) film 9 Sputtered nickel- Ni-Cr base Resin-baseInexpensive construction, if base, copper-base, or Cr-Si material basemetal of nickel or or gold base base (hardened copper is used, inaddition material sputtered at 200° C.) to characteristic of filmcombination 7.

Seventh Exemplary Embodiment

A resistor of a seventh exemplary embodiment of the present inventionand a method of manufacturing the same will be described hereinafter byreferring to accompanying figures.

FIG. 26 is a sectional view of a resistor of the seventh exemplaryembodiment of this invention.

In FIG. 26, a reference numeral 141 represents a substrate containing96% of alumina. A reference numeral 142 represents a pair of first uppersurface electrode layers composed of thin films of gold-base materialprovided on side portions of an upper surface of the substrate 141. Areference numeral 143 represents a resistance layer composed of a thinfilm of nickel-chrome base or chrome-silicon base compound providedbetween the first upper surface electrode layers 142. A referencenumeral 144 represents a protective layer composed of epoxy-group resin,or the like material provided on an upper surface of the resistancelayer 143. A reference numeral 145 represents a pair of second uppersurface electrode layers composed of silver or nickel-base conductivepowder containing resin. A reference numeral 146 represents side surfaceelectrode layers provided on side surfaces of the substrate 141 in amanner to connect with the first upper surface electrode layers 142 orthe second upper surface electrode layers 145. Reference numerals 147and 148 respectively represent nickel-plated layers and solder-platedlayers provided, as occasion demands, for a purpose of assuringreliability, etc. during soldering. Ridges of these nickel-plated layers147 and solder-plated layers 148 are rounded. Each surface area of thesolder-plated layers 148 on the side surfaces of the substrate 121 isnot more than a half of an area of the side surface of the substrate141.

The resistor of the seventh exemplary embodiment of this inventionconstructed as above is manufactured in a manner, which will bedescribed hereinafter by referring to the figures.

FIG. 27 through FIG. 29 represent a series of procedural views showing amanufacturing method of the resistor of the seventh exemplary embodimentof this invention.

First of all, electrode paste consisting of metallic-organic substance,etc. having a principal component of gold and the like material isscreen-printed in a manner not to cross over slitting grooves 150 madein a horizontal direction through an upper surface of sheet-formedsubstrate 141, which has a superior heat-resisting property and aninsulating property as it contains 96% alumina, and a surface of whichis provided with a plurality of slitting grooves 149 and 150 in avertical direction as well as in a horizontal direction in order toseparate it into rectangular strips and then into individual pieces inthe subsequent steps. After the electrode paste consisting ofmetallic-organic substance, etc. is dried, it is calcined under acondition of approximately 850° C. for about 45 minutes in abelt-conveyed continuous kiln in order to disperse only organiccomponents and to bake only metal components of the electrode paste ontothe substrate 141, to form upper surface electrode layers 142 in thinfilm, as shown in FIG. 27(a).

Next, as shown in FIG. 27(b), nickel-chrome, chrome-silicon, or the likecompound is deposited by sputtering method on an entire upper surface ofthe sheet-formed substrate 141, on which the upper surface electrodelayers 142 (not shown in this figure) are formed, to form an integralresistance layer 151.

The integral resistance layer 151 is then processed byphoto-lithographic method, the same method as normally used for LSI's,etc. to form resistance layers 143 of a desired pattern, as shown inFIG. 27(c). The resistance layers 143 are thermally treated at atemperature of approximately 300 to 400° C. in order to make them becomestable films.

Next, trimming is made to form trimmed slits 152 with a YAG laser, asshown in FIG. 28(a) in order to correct resistance values of theresistance layers 143 to a predetermined value. Trimming probes formeasuring a resistance value are set on the upper surface electrodelayers 142 in this process. The trimming is made by serpentine cuttingmethod (a plurality of straight cuts), which is capable of adjusting theresistance freely from a low value to a high value.

Epoxy-base resin paste is screen-printed to form a printing pattern ofindividual protective layers corresponding to their respectiveresistance layers 143, as shown in FIG. 28(b), in order to protect theresistance layers 143, of which resistance values have been corrected.Then, the epoxy-base resin paste is thermally set to form the protectivelayers 144 under a condition of approximately 200° C. for about 30minutes in a belt-conveyed continuous hardening kiln in order to ensurea firm adhesion to the substrate 141. For this process, the printingpattern of the protective layers may be made in such a shape that theprotective layers cross over the slitting grooves 149 of verticaldirection, and connectively cover a plurality of the horizontallyaligned resistance layers 143.

Next, second upper surface electrode layers 145 are formed as shown inthe same figure by screen-printing conductive paste composed ofsilver-base or nickel-base conductive powder containing resin in amanner to cover the upper surface electrode layers 142, followed bythermally setting them in a belt-conveyed continuous hardening kilnunder a condition of approximately 200° C. for about 30 minutes in orderto ensure a firm adhesion to the substrate 141.

Subsequently, as shown in FIG. 28(c), side surface electrode layers 146comprising a thin film of nickel-chrome base compound are formed bysputtering in a manner to cross over the slitting grooves of horizontaldirection (not shown in the figure), and to electrically connect withthe upper surface electrode layers 142. In this process, a resist layeris formed in advance in an area other than portions where the sidesurface electrode layers are formed. After a nickel-chrome layer isformed by sputtering over an entire surface of the substrate, thenickel-chrome layer in the area other than the side surface electrodelayers is removed at the same time the resist layer is removed bylift-off method.

Then, the substrate 141 in a sheet-form is subjected to a primaryseparation into rectangular substrate strips 153, as shown in FIG.29(a), by splitting it along the slitting grooves 150 of horizontaldirection in the substrate 141. When this is done, the side surfaceelectrode layers 146 lie in their respective positions on the sidesurfaces along a longitudinal direction of the rectangular substratestrips 153 down to the depth of the slitting grooves 150 of horizontaldirection.

Finally, as a preparatory process for plating exposed surfaces of thesecond upper surface electrode layers 145 and the side surface electrodelayers 146, a secondary separation is made to separate the rectangularsubstrate strips 153 into individual substrate pieces 154, as shown inFIG. 29(b). A resistor is now completed when a nickel-plated layer, asan intermediate layer (not shown in the figure), and a solder-platedlayer, as an outer layer (not shown in the figure), are formed by meansof electroplating on exposed surfaces of the second upper surfaceelectrode layers 145 and the side surface electrode layers 146, ifnecessary in order to prevent electrode-erosion during soldering and toassure reliability of the soldering.

The resistor of the seventh exemplary embodiment of this inventionconstructed and manufactured as above provides the same advantages aswhat has been described in the sixth exemplary embodiment, when it issoldered on a mount board, and therefore they will not be described.

In addition, similar effect can be attained with other combinations ofthe first upper surface electrode layers 142, the second upper surfaceelectrode layers 145, the resistance layer 143 and the protective layer144, beside the above combination in the structure of the seventhexemplary embodiment of this invention. These combinations and theirrespective characteristics are outlined in Table 7.

TABLE 7 First upper Second upper surface surface Com- electrodeelectrode Resistance Protective bina- layers layers layer layer tion 142145 143 144 Characteristics 1 Silver-base or Silver-base or RutheniumGlass-base High resistance to gold-base gold-base oxide-base materialhumidity. conductive conductive material (calcined powder and powder and(calcined at 600° C.) glass (calcined glass (calcined at 850° C.) at850° C.) at 600° C.) 2 Silver-base or Silver-base or RutheniumResin-base Same characteristic gold-base nickel-base oxide-base materialas combination 1 conductive material and material (hardened of Table 1powder and resin (calcined at 200° C.) glass (calcined (hardened at at850° C.) at 850° C.) 200° C.) 3 Silver-base or Silver-base or Ni-Cr baseResin-base Same as above. gold-base nickel-base or Cr-Si materialconductive material and base (hardened powder and resin sputtered at200° C.) glass (hardened at film (calcined at 200° C.) 850° C.) 4Gold-base Silver-base or Ruthenium Glass-base Same characteristicorganic metal gold-base oxide-base material as combination 5 compoundconductive material (calcined of Table 1. (calcined at powder and(calcined at 600° C.) 850° C.) glass (calcined at 850° C.) at 600° C.) 5Gold-base Silver-base or Ni-Cr base Resin-base (Combination of organicmetal nickel-base or Cr-Si material second exemplary compound materialand base (hardened embodiment) (calcined at resin sputtered at 200° C.)850° C.) (hardened at film 200° C.) 6 Gold-base Silver-base or CarbonicResin-base Same characteristic organic metal nickel-base resin basematerial as combination 7 compound material and material (hardened ofTable 1. (calcined at resin (hardened at 200° C.) 850° C.) (hardened atat 200° C.) 200° C.) 7 Sputtered Silver-base or Ni-Cr base Resin-baseSame characteristic nickel-base, nickel-base or Cr-Si material ascombination 9 copper-base, material and base (hardened of Table 1. orgold base resin sputtered at 200° C.) material (hardened at film 200°C.) 8 Sputtered Silver-base or Carbonic Resin-base Same characteristicnickel-base, nickel-base resin base material as combination 9copper-base, material and material (hardened of Table 1. or gold baseresin (hardened at 200° C.) material (hardened at at 200° C.) 200° C.)

Eighth Exemplary Embodiment

A resistor of an eighth exemplary embodiment of the present inventionand a method of manufacturing the same will be described hereinafter byreferring to accompanying figures.

FIG. 30 is a sectional view of a resistor of the eighth exemplaryembodiment of this invention.

In FIG. 30, a reference numeral 161 represents a substrate containing96% of alumina. A reference numeral 162 represents upper surfaceelectrode layers composed of silver-base conductive powder containingglass, and provided on side portions of a main surface and portions ofside surfaces of the substrate 161. Ridges of these upper surfaceelectrode layers 162 are rounded. In addition, a surface area of each ofthe upper surface electrode layers 162 on the side surfaces of thesubstrate 161 is not more than a half of an area of the side surface ofthe substrate 161. A reference numeral 163 represents a resistance layerhaving a chief component of ruthenium oxide, for electrically connectingwith the upper surface electrode layers 163. A reference numeral 164represents a protective layer having a chief component of glass,provided on an upper surface of the resistance layer 163. Referencenumerals 165 and 166 respectively represent nickel-plated layers andsolder-plated layers provided, as occasion demands, for a purpose ofassuring reliability, etc. during soldering.

The resistor of the eighth exemplary embodiment of this inventionconstructed as above is manufactured in a manner, which will bedescribed hereinafter by referring to the figures.

FIG. 31 and FIG. 32 represent a series of procedural views showing amanufacturing method of the resistor of the eighth exemplary embodimentof this invention.

First, electrode paste containing silver-base conductive powder andglass is printed to form upper surface electrode layers 162, as shown inFIG. 31(a), in a manner to cross over slitting grooves 168 made in ahorizontal direction through a sheet-formed substrate 161, which has asuperior heat-resisting property and an insulating property as itcontains 96% alumina, and a surface of which is provided with aplurality of slitting grooves 167 and 168 in a vertical direction aswell as in a horizontal direction in order to separate it intorectangular strips and then into individual pieces in the subsequentsteps. The upper surface electrode layers 162 are then calcined at atemperature of approximately 850° C. in order to make them become stablefilms. During this process, the electrode paste gets into the slittinggrooves 168 of horizontal direction, and that the upper surfaceelectrode layers 162 can be formed deeply down in the slitting grooves.Generally, the slitting grooves 167 and 168 are so formed that theirdepth with respect to a thickness of the substrate 161 becomes equal toor less than a half of the thickness of the substrate 161, so as toavoid it from being cracked during handling in the manufacturingprocess.

Next, resistive paste having a principal component of ruthenium oxide isprinted to form resistance layers 163 in a manner that they connectelectrically with the upper surface electrode layers 162, as shown inFIG. 31(b). The resistance layers 163 are then calcined at a temperatureof approximately 850° C. in order to make them become stable films.

Next, trimming is made to form trimmed slits 169 with a YAG laser, asshown in FIG. 31(c) in order to correct resistance values of theresistance layers 163 to a predetermined value. The trimming is madewith trimming probes for measuring a resistance value set on the uppersurface electrode layers 162 during this process.

Another paste having a principal component of glass is printed to formprotective layers 164, as shown in FIG. 32(a), in order to protect theresistance layers 163, of which resistance values have been corrected.For this process, a printing pattern may be made in such a shape thatthe protective layers 164 cross over the slitting grooves 167 ofvertical direction to connectively cover a plurality of the horizontallyaligned resistance layers 163. The protective layers 164 are thencalcined at a temperature of approximately 600° C. in order to make thembecome stable films.

Then, the substrate 161 in a sheet-form is separated into rectangularsubstrate strips 170 by splitting it along the slitting grooves 168 ofhorizontal direction in the substrate 161, on which the upper surfaceelectrode layers 162, the resistance layers 163, the trimmed slits 169,and the protective layers 164 are formed, as shown in FIG. 32(b). Whenthis is done, the previously formed upper surface electrode layers 162lie in their respective positions on the side surfaces along alongitudinal direction of the rectangular substrate strips 170 down tothe depth of the slitting grooves 168 of horizontal direction.

As a preparatory process for plating exposed surfaces of the uppersurface electrode layers 162, the rectangular substrate strips 170 arefinally separated into individual substrate pieces 171 by splitting themalong the slitting grooves 167 of vertical direction, as shown in FIG.32(c). A resistor is now completed when a nickel-plated layer, as anintermediate layer (not shown in the figure), and a solder-plated layer,as an outer layer (not shown in the figure), are formed by means ofelectroplating on exposed surfaces of the upper surface electrode layers162 in order to prevent electrode-erosion during soldering and to assurereliability of the soldering.

The resistor of the eighth exemplary embodiment of this inventionconstructed and manufactured as above was soldered on a mount board. Theresistor was mounted with the surface having the protective layer down,and soldered with both the upper surface electrode layers (not shown inthe figure) and the resistance layer on side surfaces of the substrate,as shown in a sectional view of FIG. 33(a) depicting a mounted position.However, since areas in the side surfaces, whereon the electrodes areformed, were so small, fillets 173 were barely formed. Accordingly, anactual mount area 176 came to the sum of a component area 174 and areas175 required for soldering the side surfaces of this component, as shownin a plan view of FIG. 33(b) depicting the mounted position. Theinvention could attain a reduction of approximately 20% in the mountarea as compared to a component of the prior art, in the case of asquare-tip resistor in a size of 0.6×0.3 mm.

Therefore, the structure according to the eighth exemplary embodiment ofthe present invention requires a small area on a mount board to formfillets of soldering, because of the small areas of the side surfaceelectrodes on the resistor, and thereby it can reduce the mount areas.

In the eighth exemplary embodiment of this invention, if solder-platedlayers 166 and the protective layer 164 are formed to be on the sameplane, or if the solder-plated layers 166 are formed to be higher thanthe protective layer 164, the resistor is not likely to allow a gapbetween the solder-plated layers 166 and a land pattern, when it ismounted, thereby further improving quality of mounting.

In addition, other characteristics (specified in Table 8) can beimproved in this eighth exemplary embodiment of the invention, if theupper surface electrode layers 162 and the protective layer 164 areconstituted of combinations shown in Table 8.

TABLE 8 Com- Upper surface bin- electrode Protective Characteristicsation layers 162 layer 164 to be improved 1 Gold-base Glass-baseImprovement in loaded-life conductive powder material characteristic dueto low ion and glass (calcined at migration (calcined at 600° C.) 850°C.) 2 Silver-base Resin-base No variation in resistance conductivepowder material value in manufacturing and glass (hardened at process,and small deviation (calcined at 200° C.) in resistance value of 850°C.) products, due to low processing temperature of protective layer 34.3 Gold-base Resin-base Both characteristics of above conductive powdermaterial combinations 1 and 2. and glass (hardened at (calcined at 200°C.) 850° C.) 4 Gold-base organic Glass-base Same characteristics asabove metal compound material combinations 1, and low (calcined at(calcined at manufacturing cost due to less 850° C.) 600° C.) amount ofgold used than combination 1. 5 Gold-base organic Resin-base Bothcharacteristics of above metal compound material combinations 3 and 4.(calcined at (hardened at 850° C.) 200° C.)

In addition, it is easily conceivable that the mount area can be furtherreduced if the side surface electrodes are not formed in the eighthexemplary embodiment of this invention. However, if the side surfaceelectrodes are not formed, the resistor forms no fillet at all, therebygiving rise to a problem that makes an automated inspection by imagerecognition inexecutable, in consideration of the fact that inspectionof soldering is usually carried out by means of image recognition aftermounting components in the current manufacturing process of electronicdevices.

Ninth Exemplary Embodiment

A resistor of a ninth exemplary embodiment of the present invention anda method of manufacturing the same will be described hereinafter byreferring to accompanying figures.

FIG. 34 is a sectional view of a resistor of the ninth exemplaryembodiment of this invention.

In FIG. 34, a reference numeral 181 represents a substrate containing96% of alumina. A reference numeral 182 represents upper surfaceelectrode layers provided by sputtering gold-base material on sideportions of a main surface and portions of side surfaces of thesubstrate 181. Ridges of these upper surface electrode layers 182 arerounded. In addition, a surface area of each of the upper surfaceelectrode layers 182 on the side surfaces of the substrate 181 is notmore than a half of an area of the side surface of the substrate 181. Areference numeral 183 represents a resistance layer having a chiefcomponent of ruthenium oxide, for electrically connecting with the uppersurface electrode layers 182. A reference numeral 184 represents aprotective layer having a chief component of glass, provided on an uppersurface of the resistance layer 183. Reference numerals 185 and 186respectively represent nickel-plated layers and solder-plated layersprovided, as occasion demands, for a purpose of assuring reliability,etc. during soldering.

The resistor of the ninth exemplary embodiment of this inventionconstructed as above is manufactured in a manner, which will bedescribed hereinafter by referring to the figures.

FIG. 35 and FIG. 36 represent a series of procedural views showing amanufacturing method of the resistor of the ninth exemplary embodimentof this invention.

First, gold is deposited in a form of film by sputtering method on anentire upper surface of a sheet-formed substrate 181, which has asuperior heat-resisting property and an insulating property as itcontains 96% alumina; and a surface of which is provided with aplurality of slitting grooves 187 and 188 in a vertical direction aswell as in a horizontal direction in order to separate it intorectangular strips and then into individual pieces in the subsequentsteps. Further, upper surface electrode layers 182 having a desiredelectrode pattern are formed, as shown in FIG. 35(a), byphoto-lithographic method which is normally used for LSI's, and thelike. The upper surface electrode layers 182 are subjected to a heattreatment at a temperature of approximately 300 to 400° C. in order tomake them become stable films. During this process, the upper surfaceelectrode layers 182 get into slitting grooves 188 of horizontaldirection, and the upper surface electrode layers 182 can be formeddeeply down in the slitting grooves. Generally, the slitting grooves 187and 188 are so formed that their depth with respect to a thickness ofthe substrate 181 becomes equal to or less than a half of the thicknessof the substrate 181, so as to avoid it from being cracked duringhandling in the manufacturing process.

Next, resistive paste having a principal component of ruthenium oxide isprinted to form resistance layers 183 in a manner that they connectelectrically with the upper surface electrode layers 182, as shown inFIG. 35(b). The resistance layers 183 are then calcined at a temperatureof approximately 850° C. in order to make them become stable films.

Next, trimming is made to form trimmed slits 189 with a YAG laser, asshown in FIG. 35(c) in order to correct resistance values of theresistance layers 183 to a predetermined value. The trimming is madewith trimming probes for measuring a resistance value set on the uppersurface electrode layers 182 during this process.

Another paste having a principal component of glass is printed to formprotective layers 184, as shown in FIG. 36(a), in order to protect theresistance layers 183, of which resistance values have been corrected.For this process, a printing pattern may be made in such a shape thatthe protective layers 184 cross over the slitting grooves 187 ofvertical direction to connectively cover a plurality of the horizontallyaligned resistance layers 183. The protective layers 184 are thencalcined at a temperature of approximately 600° C. in order to make thembecome stable films.

Then, the substrate 181 in a sheet-form, on which the upper surfaceelectrode layers 182, the resistance layers 183, the trimmed slits 189,and the protective layers 184 are formed, is separated into rectangularsubstrate strips 190 by splitting it along the slitting grooves 188 ofhorizontal direction in the substrate 181, as shown in FIG. 36(b). Whenthis is done, the previously formed upper surface electrode layers 182lie in their respective positions on the side surfaces along alongitudinal direction of the rectangular substrate strips 190 down tothe depth of the slitting grooves 188 of horizontal direction.

As a preparatory process for plating exposed surfaces of the uppersurface electrode layers 182, the rectangular substrate strips 190 arefinally separated into individual substrate pieces 191 by splitting themalong the slitting grooves 187 of vertical direction, as shown in FIG.36(c). A resistor is now completed when a nickel-plated layer, as anintermediate layer (not shown in the figure), and a solder-plated layer,as an outer layer (not shown in the figure), are formed by means ofelectroplating on exposed surfaces of the upper surface electrode layers182 in order to prevent electrode-erosion during soldering and to assurereliability of the soldering.

The resistor of the ninth exemplary embodiment of this inventionconstructed and manufactured as above provides the same advantages aswhat has been described in the eighth exemplary embodiment, when it issoldered on a mount board, and therefore they will not be described.

In addition, other characteristics (specified in Table 9) can beimproved in this ninth exemplary embodiment of the invention, if theupper surface electrode layers 182, resistance layer 183 and theprotective layer 184 are constituted of combinations shown in Table 9.

TABLE 9 Com- Upper surface Resistance Protective bina- electrode layerslayer layer Characteristics to be tion 182 183 184 improved 6 Sputteredgold- Ruthenium Resin-base No variation in base material oxide-basematerial manufacturing process, and (heat-treated at material (hardenedsmall deviation in resistance 300-400° C.) (calcined at 200° C.) valueof products, due to low at 850° C.) processing temperature of protectivelayer 7 Sputtered gold- Carbonic- Resin-base Same characteristic asabove base material resin base material combination 6, with less cost(heat-treated at material (hardened and capable of saving 300-400° C.)(hardened at 200° C.) electric energy due to lower at 200° C.) processtemperature of resistance layer than combination 6. 8 SputteredCarbonic- Resin-base Same characteristic as above nickel-base resin basematerial combination 7, with less material material (hardenedmanufacturing cost due to (heat-treated at (hardened at 200° C.) use ofbase metal for 300-400° C.) at 200° C.) electrode material as opposed tocombination 7.

Tenth Exemplary Embodiment

A resistor of a tenth exemplary embodiment of the present invention anda method of manufacturing the same will be described hereinafter byreferring to accompanying figures.

FIG. 37 is a sectional view of a resistor of the tenth exemplaryembodiment of this invention.

In FIG. 37, a reference numeral 201 represents a substrate containing96% of alumina. A reference numeral 202 represents first upper surfaceelectrode layers composed of silver-base conductive powder containingglass, provided on side portions of a main surface and portions of sidesurfaces of the substrate 201. A surface area of each of the first uppersurface electrode layers 202 on the side surfaces of the substrate 201is not more than a half of an area of the side surface of the substrate201. A reference numeral 203 represents a resistance layer having achief component of ruthenium oxide, for electrically connecting with thefirst upper surface electrode layers 202. A reference numeral 204represents a protective layer having a chief component of glass,provided on an upper surface of the resistance layer 203. A referencenumeral 205 represents second upper surface electrode layers composed ofsilver-base conductive powder containing glass, provided on uppersurfaces of the first upper surface electrode layers 202. Ridges of thesecond upper surface electrode layers 205 are rounded. Referencenumerals 206 and 207 respectively represent nickel-plated layers andsolder-plated layers provided, as occasion demands, for a purpose ofassuring reliability, etc. during soldering.

The resistor of the tenth exemplary embodiment of this inventionconstructed as above is manufactured in a manner, which will bedescribed hereinafter by referring to the figures.

FIG. 38 and FIG. 39 represent a series of procedural views showing amanufacturing method of the resistor of the tenth exemplary embodimentof this invention.

First, electrode paste containing silver-base conductive powder andglass is printed to form first upper surface electrode layers 202, asshown in FIG. 38(a), in a manner to cross over slitting grooves 209 madein a horizontal direction through a sheet-formed substrate 201, whichhas a superior heat-resisting property and an insulating property as itcontains 96% alumina, and a surface of which is provided with aplurality of slitting grooves 208 and 209 in a vertical direction aswell as in a horizontal direction in order to separate it intorectangular strips and then into individual pieces in the subsequentsteps. The first upper surface electrode layers 202 are then calcined ata temperature of approximately 850° C. in order to make them becomestable films. During this process, the electrode paste gets into theslitting grooves 209 of horizontal direction, thereby the first uppersurface electrode layers 202 can be formed down deeply in the slittinggrooves. Generally, the slitting grooves 208 and 209 are so formed thattheir depth with respect to a thickness of the substrate 201 becomesequal to or less than a half of the thickness of the substrate 201, soas to avoid it from being cracked during handling in the manufacturingprocess.

Next, resistive paste having a principal component of ruthenium oxide isprinted to form resistance layers 203 in a manner that they connectelectrically with the first upper surface electrode layers 202, as shownin FIG. 38(b). The resistance layers 203 are then calcined at atemperature of approximately 850° C. in order to make them become stablefilms.

Next, trimming is made to form trimmed slits 210 with a YAG laser, asshown in FIG. 38(c) in order to correct resistance values of theresistance layers 203 to a predetermined value. The trimming is madewith trimming probes for measuring a resistance value set on the firstupper surface electrode layers 202 during this process.

Another paste having a principal component of glass is printed to formprotective layers 204, as shown in FIG. 39(a), in order to protect theresistance layers 203, of which resistance values have been corrected.For this process, a printing pattern may be made in such a shape thatthe protective layers 204 cross over the slitting grooves 208 ofvertical direction to connectively cover a plurality of the horizontallyaligned resistance layers 203. The protective layers 204 are thencalcined at a temperature of approximately 600° C. in order to make thembecome stable films.

Next, electrode paste containing silver-base conductive powder and glassis printed to form second upper surface electrode layers 205 on uppersurfaces of the first upper surface electrode layers 202, as shown inFIG. 39(b), in a manner not to cross over slitting grooves 209 ofhorizontal direction. For this process, the printing pattern of thesecond upper surface electrode layers 205 may be made in such a shapethat the second upper surface electrode layers cross over the slittinggrooves 208 of vertical direction, above the plurality of horizontallyaligned first upper surface electrode layers 202. The second uppersurface electrode layers 205 are then calcined at a temperature ofapproximately 600° C. in order to make them become stable films.

Then, the substrate 201 in a sheet-form, on which the first uppersurface electrode layers 202, the resistance layers 203, the trimmedslits 210, the protective layers 204 and the second upper surfaceelectrode layers 205 are formed, is separated into rectangular substratestrips 211 by splitting it along the slitting grooves 209 of horizontaldirection in the substrate 201, as shown in FIG. 39(c). When this isdone, the previously formed first upper surface electrode layers 202 liein their respective positions on the side surfaces along a longitudinaldirection of the rectangular substrate strips 211 down to the depth ofthe slitting grooves 209 of horizontal direction.

As a preparatory process for plating exposed surfaces of the first uppersurface electrode layers 202 and the second upper surface electrodelayers 205, the rectangular substrate strips 211 are finally separatedinto individual substrate pieces 212 by splitting them along theslitting grooves 208 of vertical direction, as shown in FIG. 39(d). Aresistor is now completed when a nickel-plated layer, as an intermediatelayer (not shown in the figure), and a solder-plated layer, as an outerlayer (not shown in the figure), are formed by means of electroplatingon exposed surfaces of the first upper surface electrode layers 202 andthe second upper surface electrode layers 205 in order to preventelectrode-erosion during soldering and to assure reliability of thesoldering.

The resistor of the tenth exemplary embodiment of this inventionconstructed and manufactured as above was soldered on a mount board. Theresistor was mounted with the surface having the protective layer down,and soldered with both the upper surface electrode layers (not shown inthe figure) and the resistance layer on sides of the substrate, as shownin a sectional view of FIG. 40(a) depicting a mounted position. However,since areas in the side surfaces, whereon electrodes are formed, were sosmall, fillets 213 were barely formed. Accordingly, an actual mount area216 came to the sum of a component area 214 and areas 215 required forsoldering the side surfaces of this component, as shown in a plan viewof FIG. 40(b) depicting the mounted position. The invention could attaina reduction of approximately 20% in the mount area as compared to acomponent of the prior art, in the case of a square-tip resistor in asize of 0.6×0.3 mm.

Therefore, the structure according to the present invention requires asmall area on a mount board to form fillets of soldering, because of thesmall areas of the side surface electrodes on the resistor, and therebyit can reduce the mount areas.

In the tenth exemplary embodiment of this invention, if solder-platedlayers 207 and the protective layer 204 are formed to be on the sameplane, or if the solder-plated layers 207 are formed to be higher thanthe protective layer 204, the resistor is not likely to allow a gapbetween the solder-plated layers 207 and a land pattern, when it ismounted, thereby further improving quality of mounting.

In addition, other characteristics (specified in Table 10) can beimproved in this tenth exemplary embodiment of the invention, if thefirst upper surface electrode layers 202, the protective layer 204 andthe second upper surface electrode layers 205 are constituted ofcombinations shown in Table 10.

TABLE 10 Second First upper upper surface surface Com- electrodeelectrode Protective bina- layers layers layer Characteristics to betion 202 205 204 improved 1 Silver-base Silver-base Resin-base Novariation in resistance conductive conductive material value duringmanufact- powder and powder and (hardened uring process, and small glassresin at deviation in resistance (calcined at (hardened at 200° C.)value of products, 850° C.) 200° C.) due to low processing temperatureof pro- tective layer 204. 2 Silver-base Nickel-base Resin-base Samecharacteristic as conductive conductive material above combination 1,powder and powder and (hardened with less manufacturing glass resin atcost due to use of (calcined at (hardened at 200° C.) base metal forsecond 850° C.) 200° C.) upper surface electrode layers 205. 3Silver-base Silver-base Glass-base Improvement in loaded- conductiveconductive material life characteristic due powder and powder and(hardened to low ion migration. glass glass at (calcined at (calcined at600° C.) 850° C.) 600° C.) 4 Gold-base Silver-base Resin-base Bothcharacteristics of conductive conductive material above combinationspowder and powder and (hardened 1 and 3. glass resin at (calcined at(hardened at 200° C.) 850° C.) 200° C.) 5 Gold-base Nickel-baseResin-base Both characteristics of conductive conductive material abovecombinations powder and powder and (hardened 2 and 3. glass resin at(calcined at (hardened at 200° C.) 850° C.) 200° C.) 6 Gold-baseSilver-base Glass-base Same characteristic as organic conductivematerial above combination 3, metal powder and (hardened and low costdue to compound glass at reduction in amount (calcined at (calcined at600° C.) of gold used. 850° C.) 600° C.) 7 Gold-base Silver-baseResin-base Both characteristics of organic conductive material abovecombinations metal powder and (hardened 1 and 6. compound resin at(calcined at (hardened at 200° C.) 850° C.) 200° C.) 8 Gold-baseNickel-base Resin-base Both characteristics of organic conductivematerial above combinations metal powder and (hardened 2 and 6. compoundresin at (calcined at (hardened at 200° C.) 850° C.) 200° C.)

In addition, it is easily conceivable that the mount area can be furtherreduced if electrodes are not formed on the side surfaces in the tenthexemplary embodiment of this invention. However, if the electrodes arenot formed on the side surfaces, the resistor forms no fillet at all,thereby giving rise to a problem that makes an automated inspection byimage recognition inexecutable, in consideration of the fact thatinspection of soldering is usually carried out by means of imagerecognition after mounting components in the current manufacturingprocess of electronic devices.

Eleventh Exemplary Embodiment

A resistor of an eleventh exemplary embodiment of the present inventionand a method of manufacturing the same will be described hereinafter byreferring to accompanying figures.

FIG. 41 is a sectional view of a resistor of the eleventh exemplaryembodiment of this invention.

In FIG. 41, a reference numeral 221 represents a substrate containing96% of alumina. A reference numeral 222 represents first upper surfaceelectrode layers provided on side portions of a main surface andportions of side surfaces of the substrate 221 by means of sputteringgold-base material. A surface area of each of the first upper surfaceelectrode layers 222 on the side surfaces of the substrate 221 is notmore than a half of an area of the side surface of the substrate 221. Areference numeral 223 represents a resistance layer having a chiefcomponent of ruthenium oxide, for electrically connecting with the firstupper surface electrode layers 222. A reference numeral 224 represents aprotective layer having a chief component of glass, provided on an uppersurface of the resistance layer 223. A reference numeral 225 representssecond upper surface electrode layers composed of silver-base conductivepowder containing glass, provided on upper surfaces of the first uppersurface electrode layers 222. Ridges of the second upper surfaceelectrode layers 225 are rounded. Reference numerals 226 and 227respectively represent nickel-plated layers and solder-plated layersprovided, as occasion demands, for a purpose of assuring reliability,etc. during soldering.

The resistor of the eleventh exemplary embodiment of this inventionconstructed as above is manufactured in a manner, which will bedescribed hereinafter by referring to the figures.

FIG. 42 and FIG. 43 represent a series of procedural views showing amanufacturing method of the resistor of the eleventh exemplaryembodiment of this invention.

First, gold is deposited in a form of film by sputtering method on anentire upper surface of a sheet-formed substrate 221, which has asuperior heat-resisting property and an insulating property as itcontains 96% alumina, and a surface of which is provided with aplurality of slitting grooves 228 and 229 in a vertical direction aswell as in a horizontal direction in order to separate it intorectangular strips and then into individual pieces in the subsequentsteps. Further, first upper surface electrode layers 222 having adesired electrode pattern are formed, as shown in FIG. 42(a), byphoto-lithographic method which is normally used for LSI's, and thelike. The first upper surface electrode layers 222 are subjected to heattreatment at a temperature of approximately 300 to 400° C. in order tomake them become stable films. During this process, the first uppersurface electrode layers 222 get into slitting grooves 229 of horizontaldirection, thereby the upper surface electrode layers 222 can be formeddown deeply in the slitting grooves. Generally, the slitting grooves 228and 229 are so formed that their depth with respect to a thickness ofthe substrate 221 becomes equal to or less than a half of the thicknessof the substrate 221, so as to avoid it from being cracked duringhandling in the manufacturing process.

Next, resistive paste having a principal component of ruthenium oxide isprinted to form resistance layers 223 in a manner that they connectelectrically with the first upper surface electrode layers 222, as shownin FIG. 42(b). The resistance layers 223 are then calcined at atemperature of approximately 850° C. in order to make them become stablefilms.

Next, trimming is made to form trimmed slits 230 with a YAG laser, asshown in FIG. 42(c) in order to correct resistance values of theresistance layers 223 to a predetermined value. The trimming is madewith trimming probes for measuring a resistance value set on the firstupper surface electrode layers 222 during this process.

Another paste having a principal component of glass is printed to formprotective layers 224, as shown in FIG. 43(a), in order to protect theresistance layers 223, of which resistance values have been corrected.For this process, a printing pattern may be made in such a shape thatthe protective layers 224 cross over the slitting grooves 228 ofvertical direction to connectively cover a plurality of the horizontallyaligned resistance layers 223. The protective layers 224 are thencalcined at a temperature of approximately 600° C. in order to make thembecome stable films.

Next, electrode paste containing silver-base conductive powder and glassis printed to form second upper surface electrode layers 225 on uppersurfaces of the first upper surface electrode layers 222, as shown inFIG. 43(b), in a manner not to cross over slitting grooves 229 ofhorizontal direction. The second upper surface electrode layers 225 arethen calcined at a temperature of approximately 600° C. in order to makethem become stable films.

Then, the substrate 221 in a sheet-form on which the first upper surfaceelectrode layers 222, the resistance layers 223, the trimmed slits 230,the protective layers 224 and second upper surface electrode layers 225are formed, is separated into rectangular substrate strips 231 bysplitting it along the slitting grooves 229 of horizontal direction inthe substrate 221, as shown in FIG. 43(c). When this is done, thepreviously formed first upper surface electrode layers 222 lie in theirrespective positions on the side surfaces along a longitudinal directionof the rectangular substrate strips 231 down to the depth of theslitting grooves 229 of horizontal direction.

As a preparatory process for plating exposed surfaces of the first uppersurface electrode layers 222 and the second upper surface electrodelayers 225, the rectangular substrate strips 231 are finally separatedinto individual substrate pieces 232 by splitting them along theslitting grooves 228 of vertical direction, as shown in FIG. 43(d). Aresistor is now completed when a nickel-plated layer, as an intermediatelayer (not shown in the figure), and a solder-plated layer, as an outerlayer (not shown in the figure), are formed by means of electroplatingon exposed surfaces of the upper surface electrode layers 222 in orderto prevent electrode-erosion during soldering and to assure reliabilityof the soldering.

The resistor of the eleventh exemplary embodiment of this inventionconstructed and manufactured as above provides the same advantages aswhat has been described in the tenth exemplary embodiment, when it issoldered on a mount board, and therefore they will not be described.

In addition, other characteristics (specified in Table 11) can beimproved in this eleventh exemplary embodiment of the invention, if thefirst upper surface electrode layers 222, the protective layer 224 andthe second upper surface electrode layers 225 are constituted ofcombinations shown in Table 11.

TABLE 11 First upper Second surface upper Com- electrode surfaceProtective Characteristics bina- layers electrode layer to be tion 222layers 225 224 improved 9 Sputtered Silver-base Resin-base No variationin gold-base conductive material resistance value during material powderand (hardened manufacturing process, (heat- resin at 200° C.) and smalldeviation in treated at (hardened at resistance value of 300-400° 200°C.) products, due to low C.) processing temperature of protective layer224. 10 Sputtered Nickel-base Resin-base Same characteristic asgold-base conductive material above combination 9, material powder and(hardened with less manufacturing (heat- resin at 200° C.) cost due touse of base treated at (hardened at metal for second upper 300-400° 200°C.) surface electrode layers. C.) 11 Sputtered Silver-base Resin-baseRequires carbonic resin- nickel- conductive material base material forresis- base powder and (hardened tance layer. Carbonic material resin at200° C.) resin-base material can (heat- (hardened at provide saving oftreated at 200° C.) electricity. 300-400° C.)

Twelfth Exemplary Embodiment

A resistor of a twelfth exemplary embodiment of the present inventionand a method of manufacturing the same will be described hereinafter byreferring to accompanying figures.

FIG. 44 is a sectional view of a resistor of the twelfth exemplaryembodiment of this invention.

In FIG. 44, a reference numeral 241 represents a substrate containing96% of alumina. A reference numeral 242 represents first upper surfaceelectrode layers composed of silver-base conductive powder containingglass, provided on side portions of a main surface of the substrate 241.A reference numeral 243 represents a resistance layer having a chiefcomponent of ruthenium oxide, for electrically connecting with the firstupper surface electrode layers 242. A reference numeral 244 represents aprotective layer having a chief component of glass, provided on an uppersurface of the resistance layer 243. A reference numeral 245 representssecond upper surface electrode layers composed of silver-base conductivepowder containing glass, provided on upper surfaces of the first uppersurface electrode layers 242 and portions of side surfaces of thesubstrate 241. A surface area of each of the second upper surfaceelectrode layers 245 on the side surfaces of the substrate 241 is notmore than a half of an area of the side surface of the substrate 241.Ridges of the second upper surface electrode layers 245 are rounded.Reference numerals 246 and 247 respectively represent nickel-platedlayers and solder-plated layers provided, as occasion demands, for apurpose of assuring reliability, etc. during soldering.

FIG. 45 and FIG. 46 represent a series of procedural views showing amanufacturing method of the resistor of the twelfth exemplary embodimentof this invention.

First, electrode paste containing silver-base conductive powder andglass is printed to form first upper surface electrode layers 242, asshown in FIG. 45(a), in a manner to cross over slitting grooves 249 madein a horizontal direction through a sheet-formed substrate 241, whichhas a superior heat-resisting property and an insulating property as itcontains 96% alumina, and a surface of which is provided with aplurality of slitting grooves 248 and 249 in a vertical direction aswell as in a horizontal direction in order to separate it intorectangular strips and then into individual pieces in the subsequentsteps. The first upper surface electrode layers 242 are then calcined ata temperature of approximately 850° C. in order to make them becomestable films. Generally, the slitting grooves 248 and 249 are so formedthat their depth with respect to a thickness of the substrate 241becomes equal to or less than a half of the thickness of the substrate241, so as to avoid it from being cracked during handling in themanufacturing process.

Next, resistive paste having a principal component of ruthenium oxide isprinted to form resistance layers 243 in a manner that they connectelectrically with the first upper surface electrode layers 242, as shownin FIG. 45(b). The resistance layers 243 are then calcined at atemperature of approximately 850° C. in order to make them become stablefilms.

Next, trimming is made to form trimmed slits 250 with a YAG laser, asshown in FIG. 45(c) in order to correct resistance values of theresistance layers 243 to a predetermined value. The trimming is madewith trimming probes for measuring a resistance value set on the firstupper surface electrode layers 242 during this process.

Another paste having a principal component of glass is printed to formprotective layers 244, as shown in FIG. 46(a), in order to protect theresistance layers 243, of which resistance values have been corrected.For this process, a printing pattern may be made in such a shape thatthe protective layers 244 cross over the slitting grooves 248 ofvertical direction to connectively cover a plurality of the horizontallyaligned resistance layers 243, which form lines. The protective layers244 are then calcined at a temperature of approximately 600° C. in orderto make them become stable films.

Next, electrode paste containing silver-base conductive powder and glassis printed to form second upper surface electrode layers 245 on an uppersurface of the first substrate 242, as shown in FIG. 46(b), in a mannerto cross over slitting grooves 249 of horizontal direction in thesubstrate 241. During this process, the electrode paste gets into theslitting grooves 249 of horizontal direction, thereby the second uppersurface electrode layers 245 can be formed down to the deep in theslitting grooves. For this process, the printing pattern of the secondupper surface electrode layers 245 may be made in such a shape that thesecond upper surface electrode layers cross over the slitting grooves248 of vertical direction, over the plurality of horizontally alignedfirst upper surface electrode layers 242. The second upper surfaceelectrode layers 245 are then calcined at a temperature of approximately600° C. in order to make them become stable films.

Then, the substrate 241 in a sheet-form on which the first upper surfaceelectrode layers 242, the resistance layers 243, the trimmed slits 250,the protective layers 244 and the second upper surface electrode layers245 are formed, is separated into rectangular substrate strips 251 bysplitting it along the slitting grooves 249 of horizontal direction inthe substrate 241, as shown in FIG. 46(c). When this is done, thepreviously formed second upper surface electrode layers 245 lie in theirrespective positions on the side surfaces along a longitudinal directionof the rectangular substrate strips 251 down to the depth of theslitting grooves 249 of horizontal direction.

As a preparatory process for plating exposed surfaces of the secondupper surface electrode layers 245, the rectangular substrate strips 251are finally separated into individual substrate pieces 252 by splittingthem along the slitting grooves 248 of vertical direction, as shown inFIG. 46(d). A resistor is now completed when a nickel-plated layer, asan intermediate layer (not shown in the figure), and a solder-platedlayer, as an outer layer (not shown in the figure), are formed by meansof electroplating on exposed surfaces of the second upper surfaceelectrode layers 245 in order to prevent electrode-erosion duringsoldering and to assure reliability of the soldering.

The resistor of the twelfth exemplary embodiment of this inventionconstructed and manufactured as above provides the same advantages aswhat has been described in the tenth exemplary embodiment, when it issoldered on a mount board, and therefore they will not be described.

In addition, other characteristics (specified in Table 12) can beimproved in this twelfth exemplary embodiment of the invention, if thefirst upper surface electrode layers 242, the protective layer 244 andthe second upper surface electrode layers 245 are constituted ofcombinations shown in Table 12.

TABLE 12 First upper Second surface upper Com- electrode surfaceProtective Characteristics bina- layers electrode layer to be tion 242layers 245 244 improved 12 Silver- Silver-base Resin-base No variationin resis- base con- conductive material tance value during manu- ductivepowder and (hardened facturing process, and powder resin at 200° C.)small deviation in and glass (hardened at resistance value of pro-(calcined 200° C.) ducts, due to low pro- at 850° cessing temperature ofC.) protective layer 244. 13 Silver- Nickel-base Resin-base Samecharacteristic as base con- conductive material above combination 12,ductive powder and (hardened with less manufacturing powder resin at200° C.) cost due to use of base and glass (hardened at metal for secondupper (calcined 200° C.) surface electrode layers. at 850° C.) 14Gold-base Silver-base Glass-base Improvement in loaded- conductiveconductive material life characteristic due to powder powder and(hardened low ion migration. and glass glass at 600° C.) (calcined(calcined at at 850° 600° C.) C.) 15 Gold-base Silver-base Resin-baseBoth characteristics of conductive conductive material abovecombinations 12 powder powder and (hardened and 14. and glass resin at200° C.) (calcined (hardened at at 850° 200° C.) C.) 16 Gold-baseNickel-base Resin-base Both characteristics of conductive conductivematerial above combinations 13 powder powder and (hardened and 14. andglass resin at 200° C.) (calcined (hardened at at 850° 200° C.) C.) 17Gold-base Silver-base Glass-base Same characteristic as organicconductive material above combination 14, metal powder and (hardened andlow cost due to compound glass at 600° C.) reduction in amount of(calcined (calcined at gold used. at 850° 600° C.) C.) 18 Gold-baseSilver-base Resin-base Both characteristics of organic conductivematerial above combinations 12 metal powder and (hardened and 17.compound resin at 200° C.) (calcined (hardened at at 850° 200° C.) C.)19 Gold-base Nickel-base Resin-base Both characteristics of organicconductive material above combinations 13 metal powder and (hardened and17. compound resin at 200° C.) (calcined (hardened at at 850° 200° C.)C.)

Thirteenth Exemplary Embodiment

A resistor of a thirteenth exemplary embodiment of the present inventionand a method of manufacturing the same will be described hereinafter byreferring to accompanying figures.

FIG. 47 is a sectional view of a resistor of the thirteenth exemplaryembodiment of this invention.

In FIG. 47, a reference numeral 261 represents a substrate containing96% of alumina. A reference numeral 262 represents first upper surfaceelectrode layers composed of silver-base conductive powder containingglass, provided on side portions of a main surface of the substrate 261.A reference numeral 263 represents a resistance layer having a chiefcomponent of ruthenium oxide, for electrically connecting with the firstupper surface electrode layers 262. A reference numeral 264 represents aprotective layer having a chief component of glass, provided on an uppersurface of the resistance layer 263. A reference numeral 265 representssecond upper surface electrode layers formed by means of sputteringgold-base material in positions on upper surfaces and portions of sidesurfaces of the first upper surface electrode layers 262. A surface areaof each of the second upper surface electrode layers 265 on the sidesurfaces of the substrate 261 is not more than a half of an area of theside surface of the substrate 261. Ridges of the second upper surfaceelectrode layers 265 are rounded. Reference numerals 266 and 267respectively represent nickel-plated layers and solder-plated layersprovided, as occasion demands, for a purpose of assuring reliability,etc. during soldering.

The resistor of the thirteenth exemplary embodiment of this inventionconstructed as above is manufactured in a manner, which will bedescribed hereinafter by referring to the figures.

FIG. 48 and FIG. 49 represent a series of procedural views showing amanufacturing method of the resistor of the thirteenth exemplaryembodiment of this invention.

First, electrode paste containing silver-base conductive powder andglass is printed to form first upper surface electrode layers 262, asshown in FIG. 48(a), in a manner not to cross over slitting grooves 269made in a horizontal direction on a sheet-formed substrate 261, whichhas a superior heat-resisting property and an insulating property as itcontains 96% alumina, and a surface of which is provided with aplurality of slitting grooves 268 and 269 in a vertical direction aswell as in a horizontal direction in order to separate it intorectangular strips and then into individual pieces in the subsequentsteps.

Next, resistive paste having a principal component of ruthenium oxide isprinted to form resistance layers 263 in a manner that they connectelectrically with the first upper surface electrode layers 262, as shownin FIG. 48(b). The resistance layers 263 are then calcined at atemperature of approximately 850° C. in order to make them become stablefilms.

Next, trimming is made to form trimmed slits 270 with a YAG laser, asshown in FIG. 48(c) in order to correct resistance values of theresistance layers 263 to a predetermined value. The trimming is madewith trimming probes for measuring a resistance value set on the firstupper surface electrode layers 262 during this process.

Another paste having a principal component of glass is printed to formprotective layers 264, as shown in FIG. 49(a), in order to protect theresistance layers 263, of which resistance values have been corrected.For this process, a printing pattern may be made in such a shape thatthe protective layers 264 cross over the slitting grooves 268 ofvertical direction to connectively cover a plurality of the horizontallyaligned resistance layers 263. The protective layers 264 are thencalcined at a temperature of approximately 600° C. in order to make thembecome stable films.

Resist material composed of resin is coated over an entire upper surfaceof the substrate 261, and openings having a film-forming pattern of the,desired second upper surface electrode layers 265 are made in the resistmaterial by photo-lithographic method, as shown in FIG. 49(b).Furthermore, gold is deposited in a form of film on the entire uppersurface of the substrate 261 by sputtering method, and the resistmaterial is then removed except for portions of the film-forming patternfor the desired second upper surface electrode layers 265. These stepscompose the second upper surface electrode layers 265. During the aboveprocess, the second upper surface electrode layers 265 get into theslitting grooves 269 of horizontal direction, and thereby the secondupper surface electrode layers 265 can be formed down deeply in theslitting grooves.

Generally, the slitting grooves 268 and 269 are so formed that theirdepth with respect to a thickness of the substrate 261 becomes equal toor less than a half of the thickness of the substrate 261, so as toavoid it from being cracked during handling in the manufacturingprocess.

Then, the substrate 261 in a sheet-form, on which the first uppersurface electrode layers 262, the resistance layers 263, the trimmedslits 270, the protective layers 264 and the second upper surfaceelectrode layers 265 are formed, is separated into rectangular substratestrips 271 by splitting it along the slitting grooves 269 of horizontaldirection in the substrate 261, as shown in FIG. 49(c). When this isdone, the previously formed second upper surface electrode layers 265lie in their respective positions on the side surfaces along alongitudinal direction of the rectangular substrate strips 271 down tothe depth of the slitting grooves 269 of horizontal direction.

As a preparatory process for plating exposed surfaces of the uppersurface electrode layers 265, the rectangular substrate strips 271 arefinally separated into individual substrate pieces 272 by splitting themalong the slitting grooves 268 of vertical direction, as shown in FIG.49(d). A resistor is now completed when a nickel-plated layer, as anintermediate layer (not shown in the figure), and a solder-plated layer,as an outer layer (not shown in the figure), are formed by means ofelectroplating on exposed surfaces of the second upper surface electrodelayers 265 in order to prevent electrode-erosion during soldering and toassure reliability of the soldering.

The resistor of the thirteenth exemplary embodiment of this inventionconstructed and manufactured as above provides the same advantages aswhat has been described in the tenth exemplary embodiment, when it issoldered on a mount board, and therefore they will not be described.

In addition, other characteristics (specified in Table 13) can beimproved in this thirteenth exemplary embodiment of the invention, ifthe first upper surface electrode layers 262, the protective layer 264and the second upper surface electrode layers 265 are constituted ofcombinations shown in Table 13.

TABLE 13 First upper Second surface upper Com- electrode surfaceProtective Characteristics bina- layers electrode layer to be tion 262layers 265 264 improved 20 Silver- Sputtered Resin-base No variation inresis- base con- gold-base material tance value during manu- ductivematerial (hardened facturing process, and powder (heat-treated at 200°C.) small deviation in resis- and glass at 200° C.) tance value ofproducts, (calcined due to low processing at 850° temperature ofprotective C.) layer 264. 21 Silver- Sputtered Glass-base Lessmanufacturing cost base con- nickel-base material due to use of basemetal ductive material (calcined for second upper surface powder(hardened at at 600° C.) electrode layers. and glass 200° C.) (calcinedat 850° C.) 22 Gold-base Sputtered Glass-base Improvement in loaded-conductive gold-base material life characteristic due powder material(calcined to low ion migration. and glass (heat-treated at 600° C.)(calcined at 200° C.) at 850° C.) 23 Gold-base Sputtered Resin-base Bothcharacteristics of conductive gold-base material above combinations 20powder material (hardened and 22. and glass (heat-treated at 200° C.)(calcined at 200° C.) at 850° C.) 24 Gold-base Sputtered Glass-base Bothcharacteristics of conductive nickel-base material above combinations 21powder material (hardened and 22. and glass (heat-treated at 200° C.)(calcined at 200° C.) at 850° C.) 25 Gold-base Sputtered Resin-base Bothcharacteristics of conductive nickel-base material above combinations21, powder material (hardened 22 and 20. and glass (heat-treated at 200°C.) (calcined at 200° C.) at 850° C.) 26 Gold-base Sputtered Glass-baseSame characteristic as organic gold-base material above combination 22,metal material (calcined and low manufacturing compound (heat-treated at600° C.) cost due to reduction in (calcined at 200° C.) amount of goldused. at 850° C.) 27 Gold-base Sputtered Resin-base Same characteristicas organic gold-base material above combination 23, metal material(hardened and low manufacturing compound (heat-treated at 200° C.) costdue to reduction in (calcined at 200° C.) amount of gold used. at 850°C.) 28 Gold-base Sputtered Glass-base Same characteristic as organicgold-base material above combination 24, metal material (hardened andlow manufacturing compound (heat-treated at 200° C.) cost due toreduction in (calcined at 200° C.) amount of gold used. at 850° C.) 29Gold-base Sputtered Resin-base Same characteristic as organicnickel-base material above combination 25, metal material (hardened andlow manufacturing compound (heat-treated at 200° C.) cost due toreduction in (calcined at 200° C.) amount of gold used. at 850° C.)

INDUSTRIAL APPLICABILITY

As has been described, a resistor of the present invention comprises: asubstrate; a pair of first upper surface electrode layers provided onside portions of an upper surface toward portions of side surfaces ofthe substrate; a pair of second upper surface electrode layers providedin a manner to make electrical connections with the first upper surfaceelectrode layers; a resistance layer provided in a manner to makeelectrical connections with the second upper surface electrode layers;and a protective layer provided to cover at least an upper surface ofthe resistance layer. The above-described structure provides theresistor with side surface electrodes having a small surface area, sincethe pair of first upper surface electrode layers are disposed on sideportions of the upper surface toward portions of the side surfaces ofthe substrate. Because the resistor is soldered with the side surfaceelectrodes of the small area, it can reduce an area required to formfillets of soldering, when it is soldered on a mount board. Accordingly,the resistor is able to reduce an actual mount area, including solderingportions, on the mount board.

What is claimed is:
 1. A discrete resistor comprising: a substratehaving an upper surface, side surfaces and a bottom surface, said sidesurfaces each having a length from said upper surface to said bottomsurface; a pair of electrodes including respective electrode Sayers,each being disposed on and in contact with respective opposite endportions of said upper surface of said substrate and on respectiveportions of said side surfaces of said substrate, said portion beinglimited to no more than half the length of said side surfaces from saidupper surface; further respective conductive layers outside of saidelectrode layers along said respective portions of said side surfaces ofsaid substrate, at least half the length of said side surfaces from saidbottom surface being free of any conductive layers; a resistor layerdisposed on said upper surface of said substrate, said resistor layerelectrically connected to each of said pair of electrodes; and aprotective layer covering at least an upper surface of said resistorlayer.
 2. The resistor of claim 1, wherein said pair of electrodesincludes a first electrode and a second electrode, said first electrodeand second electrode being electrically connected, said first electrodebeing disposed on an upper surface of said substrate, said secondelectrode being disposed on said first electrode and on a portion ofsaid side surface of said substrate, said portion being no more thanhalf the length of said side surface from said upper surface, and saidresistor layer being electrically connected to said first electrode. 3.The resistor of claim 1, wherein said pair of electrodes includes afirst electrode and a second electrode, said first electrode and secondelectrode being electrically connected, said first electrode beingdisposed on an end portion of said upper surface and a portion of saidside surface of said substrate, said portion being no more than half thelength of said side surface from said upper surface, said secondelectrode being disposed on said first electrode, and said resistorlayer being electrically connected to said second electrode.
 4. Theresistor of claim 1, wherein each of said pair of electrodes includes afirst electrode and a second electrode, said first electrode and secondelectrode being electrically connected, said first electrode beingdisposed on an upper surface and a portion of said side surface of saidsubstrate, said portion being no more than half the length of said sidesurface from said upper surface, said second electrode being disposed onan upper surface of said first electrode, and said resistor layer beingelectrically connected to said first electrode.
 5. The resistor of claim2, further comprising a third electrode disposed on said secondelectrode and electrically connected to said second electrode.
 6. Theresistor of claim 3, further comprising a third electrode disposed onsaid second electrode and electrically connected to said secondelectrode.
 7. The resistor of claim 1, wherein each of said pair ofelectrodes includes a first electrode, a second electrode and a thirdelectrode, said first electrode, second electrode and third electrodebeing electrically connected, said first electrode being disposed on andin contact with an upper surface of said substrate, said secondelectrode being disposed on said first electrode, said third electrodebeing disposed on said second electrode and a portion of side surface ofsaid substrate, said portion being no more than half the length of saidside surface from said upper surface, and said resistor layer beingelectrically connected to said first electrode.
 8. The resistor of claim1, further comprising a metal plated layer covering each of said pair ofelectrodes, said plated layer being formed on the same plane with, orgreater in height than said protective layer.
 9. The resistor of claim2, further comprising a metal plated layer covering each of said pair ofelectrodes, said plated layer being formed on the same plane with, orgreater in height than said protective layer.
 10. The resistor of claim3, further comprising a metal plated layer covering each of said pair ofelectrodes, said plated layer being formed on the same plane with, orgreater in height than said protective layer.
 11. The resistor of claim4, further comprising a metal plated layer covering each of said pair ofelectrodes, said plated layer being formed on the same plane with, orgreater in height than said protective layer.
 12. The resistor,of claim5, further comprising a metal plated layer covering each of said pair ofelectrodes, said plated layer being formed on the same plane with orgreater in height than said protective layer.
 13. The resistor of claim6, further comprising a metal plated layer covering each of said pair ofelectrodes, said plated layer being formed on the same plane with, orgreater in height than said protective layer.
 14. The resistor of claim7, further comprising a metal plated layer covering each of said pair ofelectrodes, said plated layer being formed on the same plane with, orgreater in height than said protective layer.
 15. The resistor of anyclaim 2, wherein said first electrode is one of gold base thin film andnickel base thin film.
 16. The resistor of any claim 3, wherein saidfirst electrode is one of gold base thin film and nickel base thin film.17. The resistor of any claim 4, wherein said first electrode is one ofgold base thin film and nickel base thin film.
 18. The resistor of anyclaim 5, wherein said first electrode is one of gold base thin film andnickel base thin film.
 19. The resistor of any claim 6, wherein saidfirst electrode is one of gold base thin film and nickel base thin film.20. The resistor of any claim 7, wherein said first electrode is one ofgold base thin film and nickel base thin film.
 21. A discrete resistoraccording to claim 1, wherein said pair of electrodes are one-piece.